The Refill Filling Button (better known to our customers as the yellow button) is a small but essential cartridge prep tool that we designed and 3D print right here at Refill Pen — and it ships free with every pen order.
 
What it does:
 
After sterilization, the gray rubber stopper inside an empty cartridge can stiffen up, making it stubborn to draw your peptide into. The yellow button gives you a clean, controlled way to free that stopper before you fill. 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
 
  See it in action: We filmed a short how-to video showing exactly how to use the yellow button to prep a cartridge before filling on our help page,  follow along your first time so see how to use it.
 
  Lost yours, need a spare, or stocking up for multiple pens? Order a replacement here.
 
Note: These are the exact same as the yellow button you may have received with your Pen order, the only difference is the colors.
 
  Note: 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.