How the reusable pen works

Our reusable pens use a click-ratchet barrel: each click advances the internal plunger by a fixed, calibrated increment, displacing a known volume of liquid from the glass cartridge once you've loaded a reconstituted vial. That's what makes a click count a repeatable reference point rather than an estimate.

Under the cap sits a sealed glass cartridge and a chrome collar. The cap lifts off to expose the cartridge and threaded tip; nothing about the mechanism is decorative, every part is there to keep measurement consistent across the life of the device.

Store the pen as you would any glass-cartridge lab device: upright, away from direct light and heat, and recap fully after use.