Peptide Pen Needles · 31G × 6 mm

Pen needles are not syringe needles. They are dual-ended: the outer cannula is what delivers, and a shorter rear cannula pierces the cartridge septum inside the pen. That rear end is why a syringe needle cannot be substituted.

Screw-on fitment to the pen collar, one needle per delivery. Remove and discard the needle after each use rather than leaving it attached — a needle left on a pen is both a contamination path and a leakage path, because the cartridge stays open to air through the cannula.

Sterile, single-use. For research and educational use only.