Pens
V2.5 Peptide Pen (Slim Hybrid, Open Cap)
5.0· 5 verified reviews- Open cap — needle hidden
- Slim, lighter aluminum body
- 60-unit range
- Most orders ship same day
- Free shipping over $59
- Ready to use on arrival
- 7-day guarantee
Every pen comes with a 3 mL cartridge. Starter tools are included once per order.
The V2.5 Slim Hybrid pairs the hidden-needle comfort of our open cap with the slim body and dial of the V1 and V3 — a lighter, easier-to-hold peptide pen that keeps the needle out of sight while you inject. It holds a 60-unit range in solid aluminum and dials true: one click, one unit, every time.
Slim body, hidden needle
The V2.5 is the comfort pick: an open-cap design that keeps the needle out of sight, in a lighter, slimmer aluminum body with the same precise dial as the V1 and V3. RefillPen is reusable hardware built to be used again and again. When a cartridge runs out you swap the inexpensive 3 mL cartridge, not the pen — that's the whole idea behind a refillable peptide pen. We recommend adding Spacers with this model to get every last bit of liquid out of a cartridge.
Accuracy you can trust
Accuracy is what the peptide community asks about most, and it's what our reviews single out. The dial advances one click at a time, and on the pen's 100-unit scale one click equals one unit (0.01 mL) — so the number you set is the number you draw.
Everything you need to start
Every RefillPen comes with one 3 mL cartridge, and every order includes a set of starter tools, so you can get started the day it arrives. Ordering several pens, for yourself or someone else? Each pen still gets its own cartridge, and you can add an extra starter tools set for $2 in your cart.
Common questions
How does a peptide pen work?
You load a standard 3 mL glass cartridge into the pen, attach a universal pen needle, and turn the dial to set your amount in units. On the 100-unit scale one click equals one unit (0.01 mL), so what you dial is what you draw. When the cartridge is empty you replace the cartridge, not the pen.
How long does a peptide pen last?
The pen is reusable hardware you keep and refill — you replace the low-cost 3 mL cartridge rather than the pen itself, so one pen stays in service across many cartridges.
What cartridges and needles fit?
Every RefillPen model uses the same consumables: standard 3 mL glass cartridges and universal pen needles. Individually sterilized 3 mL cartridges are about $1 each.
Is the needle visible when I inject?
The V2.5 uses an open-cap design that keeps the needle out of sight while you inject.
Not sure how many units to dial?
Use the free peptide dosing calculator on this site to find your exact units — enter your numbers and it returns the units (clicks) to set on the pen.
What's the difference between the V1, V2, V2.5, and V3?
All four are reusable peptide pens that share the same 3 mL cartridges and universal needles; they differ in cap style (open cap hides the needle, closed cap shows it), body and dial feel, and dose range. See the 'Best Reusable Peptide Pen' guide to compare them side by side.
Reviews
I keep ordering because their shipping and packaging are great. I have bought several pens from this company, and they are great. Their pens aren't cheap, but they are durable and work great.
These pens are not like the others that break in a month etc,I've bought 5 so far,and all are still in good condition 🙏
Great pen, works like a charm. The service and delivery was also excellent
Absolutely love the new pen, it is awesome! My favorite so far!
Attention to detail always impress me. Nicely done!
Complete your setup
Want the whole setup? Build a Starter Kit →
3ml Individually Packed Glass Cartridge For Pen
The $1 sterilized 3 mL glass refill that fits every RefillPen.
Halo Cartridge Holder
A filling block that holds your cartridge steady for a clean, bubble-free fill.
Color: Black
Spacers for Cartridges - 5 Count
Drop-in spacers that clear the dead space so you draw every last drop.
Spacer Color: Red
Number Labels
Slide-on numbers so every pen shows your units at a glance.
Color: Pink
RefillPen Labels
Slide-on labels so you can tell at a glance what's loaded in each pen.