Cartridges & refills
The RefillPen Filling Button
- Most orders ship same day
- Free shipping over $59
- Ready to use on arrival
- 7-day guarantee
The Yellow Refill Button — a small cartridge-prep tool we designed and 3D-print in-house, and it ships free with every pen. After sterilization a cartridge's gray rubber stopper can stiffen up; the button gives you a clean, controlled way to free it before you fill.
What it does
Press the cartridge straight down into the button and the stopper releases — no twisting, no forcing, no wasted peptide.
Why our customers swear by it
Solves the stiff-stopper problem that almost every refillable-pen user runs into post-sterilization. Designed by RefillPen — built specifically for the cartridges we sell, not a generic adapter. Included free with every pen order, and also available here as a stand-alone replacement. Compact — fits in any travel pouch or peptide kit. Durable 3D-printed construction.
Good to know
These are the exact same as the yellow button you may have received with your pen order; the only difference is the colors. Each Refill Filling Button is 3D-printed to order, so slight variations in finish are normal and part of the handmade character of the product.
Common questions
What does the yellow button do?
Sterilization can stiffen the gray stopper inside an empty cartridge, making it stubborn to draw into. The button frees it for a clean, controlled fill.
Do I need to buy one?
It ships free with every pen order. Buy extras here if you want a spare.
Button or Halo?
Both make filling easier — the button frees the stopper, the Halo braces the whole cartridge upright. Many people use them together.
Complete your setup
Want the whole setup? Build a Starter Kit →
V2 Peptide Pen
Our best-selling everyday reusable peptide pen — open cap, one click per unit.
Color: Pink Champagne - Black Dial
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
3ml Peptide Vial Travel Box
Padded hard case that keeps your 3 mL vials sorted, protected, and travel-ready.
Box Color: Black