Nate Byer

A peptide pen is a reusable, pen-shaped tool for measuring out precise, repeatable amounts of liquid from a sealed glass cartridge. You set an amount on a dial, press a button, and a plunger rod moves the cartridge’s rubber stopper forward by exactly

A reusable pen swaps cartridges for years. A disposable pen uses one cartridge start to finish. Here's how they compare on waste, convenience and long-term value.

Drawing liquid into a syringe depends on reading a scale and catching air bubbles. A pen's dial moves a screw a fixed distance per click. Here's what the research shows.

Gauge is the needle's thickness and the second number is its length. Here's what changes between 31G and 32G, why flow drops fast, and why every needle is single-use.

A 3 mL pen cartridge is four parts: a glass barrel, a rubber plunger, a sealed septum and a crimped cap. Here's what each one does and how to handle them.

Compare the PepPen V1, V2, V2 Pro, V3 and Disposable side by side: build, capacity and cartridge loading, so you can pick the right reusable peptide pen.