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How to Use a V2 Peptide Research Pen
Research Overview
A V2 peptide research pen is a reusable mechanical device designed to hold a 3 mL glass cartridge and dispense small, repeatable volumes of research solution.
At first glance, the pen can look complicated. There is a glass cartridge to load, a needle to attach, a pen to prime, and a numbered dose wheel to understand.
The good news is that the basic idea is actually very simple.
The V2 pen measures liquid volume.
The number shown on the dose wheel does not directly represent milligrams or micrograms. It tells the pen how much liquid to move out of the cartridge.
On the standard V2 60-unit pen:
1 unit = 0.01 mL
So:
- 5 units = 0.05 mL
- 10 units = 0.10 mL
- 20 units = 0.20 mL
- 30 units = 0.30 mL
- 40 units = 0.40 mL
- 50 units = 0.50 mL
- 60 units = 0.60 mL
Understanding that relationship is the key to understanding the entire V2 pen.
For research purposes only. This article explains the mechanical operation and volumetric measurement of a V2 research pen and is not intended as instructions for human or veterinary treatment.
The V2 peptide research pen is essentially a small mechanical liquid-measuring system.
Inside the pen is a 3 mL glass cartridge containing a prepared research solution.
At the back of that cartridge is a movable rubber stopper.
Inside the pen is a mechanical drive mechanism.
When the pen is operated, the drive mechanism pushes the rubber stopper forward. As the stopper moves, a measured amount of liquid is pushed out through the needle.
The amount of liquid that moves is controlled by the dose wheel at the end of the pen.
This is where many first-time users become confused.
The dose wheel does not know:
- what compound is in the cartridge;
- how many milligrams are present;
- how much diluent was used;
- what concentration was created;
- how much research material a protocol requires.
It only controls liquid volume.
That means using a V2 pen involves three separate calculations:
1. Determine the concentration
How much research material is contained in each millilitre of solution?
2. Determine the required liquid volume
How many millilitres contain the amount required by the research protocol?
3. Convert that volume into V2 units
What number should be selected on the pen?
The correct order is therefore:
Material → Concentration → Required Volume → V2 Setting
Do not begin with the dose wheel.
Begin with the solution.
The Big Picture
An easy way to understand the V2 is to imagine a bottle of concentrated juice and a measuring cup.
The glass cartridge is like the bottle.
It holds the solution.
The concentration tells you how much material is contained in that solution.
The dose wheel is like the measuring cup.
It determines how much liquid you take out.
The measuring cup does not know how strong the juice is.
In the same way, the V2 pen does not know how concentrated the research solution is.
It simply measures volume.
For example, if the V2 is set to:
20 units
the pen is being instructed to move:
0.20 mL
That is all the number 20 tells us.
It does not automatically mean:
20 mg
or
20 mcg.
How much research material is contained within that 0.20 mL depends entirely on the concentration of the solution inside the cartridge.
The simplest way to remember it
Concentration tells you WHAT is in the liquid.
Your calculation tells you HOW MUCH liquid you need.
The V2 wheel tells the pen HOW MUCH liquid to move.
How It Works
Before using the pen, it helps to understand its individual parts.
The 3 mL Glass Cartridge
The V2 uses a long, narrow glass cartridge.
This should not be confused with the small glass vial commonly used to store lyophilized research material.
The cartridge is designed specifically to fit inside the pen.
At one end is the sealed end where the pen needle connects.
At the opposite end is a movable rubber stopper.
As the rubber stopper moves forward, liquid is pushed out of the cartridge.
The Cartridge Holder
The cartridge holder is the section of the pen that surrounds and supports the glass cartridge.
The cartridge must be installed in the correct direction.
A simple rule is:
Needle end → front
Rubber stopper → back
The rubber stopper must face the mechanical drive system inside the main body of the pen.
The Internal Drive Mechanism
Inside the pen is a mechanical rod or screw.
When the dispensing mechanism is activated, this rod moves forward.
It presses against the rubber stopper at the back of the cartridge.
The stopper then moves forward and displaces liquid.
The V2 therefore works through mechanical displacement.
No electronics are required.
The Pen Needle
A compatible screw-on pen needle attaches to the front of the cartridge holder.
The needle creates the path through which liquid leaves the cartridge.
A newly assembled pen should not simply be assumed to be ready because the cartridge contains liquid.
The liquid pathway should first be established through priming.
The Dose Wheel
The dose wheel is the most important part to understand.
On the standard V2 pen:
1 unit = 0.01 mL
This means the number displayed by the pen can be converted directly into millilitres.
| V2 Setting | Liquid Volume |
|---|---|
| 1 | 0.01 mL |
| 5 | 0.05 mL |
| 10 | 0.10 mL |
| 15 | 0.15 mL |
| 20 | 0.20 mL |
| 25 | 0.25 mL |
| 30 | 0.30 mL |
| 40 | 0.40 mL |
| 50 | 0.50 mL |
| 60 | 0.60 mL |
There is also a very easy shortcut.
To convert V2 units into mL:
Units ÷ 100 = mL
For example:
20 ÷ 100 = 0.20 mL
35 ÷ 100 = 0.35 mL
50 ÷ 100 = 0.50 mL
To convert mL into V2 units:
mL × 100 = V2 units
For example:
0.10 mL × 100 = 10 units
0.25 mL × 100 = 25 units
0.40 mL × 100 = 40 units
Why Concentration Must Come First
Imagine a cartridge contains:
10 mg of research material in 2 mL of solution.
First calculate the concentration:
10 mg ÷ 2 mL = 5 mg/mL
That means every 1 mL contains 5 mg.
Suppose a laboratory protocol calls for an aliquot containing:
0.5 mg
Now calculate the liquid volume:
0.5 mg ÷ 5 mg/mL = 0.10 mL
Only now do we use the pen.
Convert 0.10 mL into V2 units:
0.10 × 100 = 10 units
The pen would therefore be set to:
10
The complete sequence is:
10 mg
↓
2 mL
↓
5 mg/mL
↓
0.5 mg required
↓
0.10 mL required
↓
10 units on the V2
The dose wheel did not calculate the 0.5 mg.
It simply measured 0.10 mL.
Putting It Into Practice
This section walks through the complete V2 procedure from beginning to end.
Follow the steps in order.
1. Inspect and Prepare Your Materials
Confirm you have the V2 pen, compatible 3 mL glass cartridge, pen needle, prepared research material, bacteriostatic water, transfer syringe/needle, and a clean work area. Inspect the cartridge for cracks, chips, damaged seals, or stopper problems.
2. Measure the Bacteriostatic Water
Using the transfer syringe, draw the required volume of bacteriostatic water. Record the amount used because it determines the final concentration.
3. Reconstitute the Research Material
Transfer the bacteriostatic water into the research vial using the appropriate laboratory procedure. Allow the material to dissolve fully without vigorous shaking.
4. Draw Up the Reconstituted Solution
Once the solution is prepared, draw it back into the transfer syringe. Confirm the intended amount has been collected and check for obvious preparation problems.
5. Fill and Inspect the Glass Cartridge
Transfer the prepared solution into the V2-compatible 3 mL glass cartridge through its sealed front end. Inspect the filled cartridge and confirm the rubber stopper remains properly positioned.
6. Load the Cartridge Into the V2 Pen
Remove the outer pen sleeve, separate the clear cartridge holder from the pen body, and place the filled cartridge into the holder with the rubber stopper toward the pen’s internal plunger.
7. Reassemble the Pen
Align the loaded cartridge holder with the threaded pen body and screw the components together until snug. Do not force or overtighten them.
8. Attach the Pen Needle
Install a compatible screw-on pen needle on the front of the cartridge holder. Remove the appropriate protective needle covers when preparing to prime the system.
9. Prime the V2 Pen and Remove Trapped Air
Hold the pen with the needle end upward. Use small settings on the dose control and advance the plunger as needed until the dispensing pathway is filled and a small amount of liquid appears at the needle tip. Repeat as necessary if a significant air space remains.
10. Reassemble and Set the Required V2 Units
Replace the outer sleeve. Calculate the required liquid volume and convert it to V2 units, then pull out and turn the dose wheel until the correct number appears in the window. The pen is now configured for the intended research dispensing step.
The V2 is now mechanically protected.
Common Mistakes & Good Research Practice
Mistake 1 — Thinking the Dose Wheel Shows Milligrams
This is the most important mistake to avoid.
20 does not mean 20 mg.
It means:
20 units = 0.20 mL
Mistake 2 — Thinking the Pen Calculates Concentration
It doesn’t.
The V2 has no way of knowing what is inside the cartridge.
Concentration must be calculated separately.
Mistake 3 — Going Directly From Milligrams to the Wheel
Do not calculate:
mg → wheel
Instead use:
mg → concentration → mL → V2 units
Mistake 4 — Installing the Cartridge Backward
Remember:
Needle end → front
Rubber stopper → back
Mistake 5 — Forcing the Cartridge
If the cartridge does not fit normally, stop.
Check its dimensions, orientation and stopper configuration.
Do not force the pen together.
Mistake 6 — Skipping Priming
Liquid being visible inside the cartridge does not guarantee that the fluid pathway through a newly attached needle has been established.
Confirm flow first.
Mistake 7 — Counting Clicks Instead of Reading the Setting
Clicks can help you feel the adjustment.
The displayed number should be your final confirmation.
Mistake 8 — Leaving a Used Needle Attached
Remove used needles according to appropriate laboratory sharps-handling procedures.
Mistake 9 — Forcing a Stiff Mechanism
A V2 that suddenly requires unusual force may have:
- an improperly seated cartridge;
- an incompatible cartridge;
- a mechanical obstruction;
- insufficient remaining liquid;
- an incorrectly positioned drive mechanism.
Stop and identify the problem.
Mistake 10 — Failing to Record the Calculation
Good research practice means documenting:
- material amount;
- diluent volume;
- calculated concentration;
- required aliquot;
- calculated liquid volume;
- V2 setting.
This creates a record that can later be checked or reproduced.
Key Takeaways
The V2 pen is easier to understand when its jobs are separated.
The cartridge holds the solution.
The concentration tells you what is in that solution.
Your calculation determines how much liquid is required.
The dose wheel tells the pen how much liquid to move.
Remember these core rules:
1 unit = 0.01 mL
10 units = 0.10 mL
20 units = 0.20 mL
50 units = 0.50 mL
60 units = 0.60 mL
And remember the calculation order:
Material → Concentration → Volume → V2 Setting
Never assume the number on the pen represents milligrams or micrograms.
If you know the concentration and calculate the required liquid volume correctly, converting that volume into a V2 setting becomes straightforward.
Sources & Further Reading
V2 Pen Technical Information
Preppin Peppers — V2 Peptide Pen, Reusable Needle-Shield, 60-Unit, 3 mL
This is currently our strongest technical source for the V2. It confirms the aluminum body, 3 mL / 300-unit cartridge, 60-unit maximum setting, draw-and-push mechanism, and important cartridge dimensions.
V2 Pen Technical Specifications — Preppin Peppers
RefillPen — Original V2 Reusable Peptide Pen, 60-Unit / 3 mL
This source confirms the 3 mL cartridge, universal pen-needle compatibility, whole-unit settings up to 60, aluminum construction, replaceable cartridges, and concealed-needle design.
Original V2 Reusable Pen — RefillPen
Pen Priming and Mechanical Operation
Eli Lilly Canada — Why Is It Important to Prime the Zepbound KwikPen?
This is a much stronger source for explaining the principle of priming. Lilly explains that priming removes air from the cartridge, confirms that the pen is operating correctly, and is verified when liquid appears at the needle tip. Their specific KwikPen controls are different from the V2, so we should cite it only for the underlying priming principle—not as V2 operating instructions.
KwikPen Priming Information — Eli Lilly Canada
We could alternatively use Lilly’s Mounjaro KwikPen priming page, which explains the same principle.
Mounjaro KwikPen Priming — Eli Lilly Canada
Related SilverLeaf Learning
For Understanding Peptide Reconstitution,
IN THIS ARTICLE
Table of Contents
Did You Know?
The V2 pen does not measure milligrams or micrograms—it measures liquid volume. On the standard 3 mL / 300-unit V2 pen, 1 unit equals 0.01 mL, so a setting of 20 means the pen is set to dispense 0.20 mL of liquid, regardless of what concentration is inside the cartridge.
Research Tip
Never try to convert milligrams directly into a V2 wheel setting without first knowing the concentration of the solution.
Write down the concentration and V2 conversion before operating the dose wheel. A few seconds of documentation can prevent a simple arithmetic mistake from becoming part of an experiment.
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