Pins are crafted to perfection and help give the Painless, Sharpest line you will ever get. Perfect Taper- Length and Size are mastered, based on continuous feedback received from renowned Artists during Their designs and crafting process. Pins are Soldered by Automatic Machines in 46 different shapes and configurations, making each needle consistently the same. Membrane is made of Elastomeric Silicon, gives consistent and smoothest movement to the needles. Guaranteed 100% Ink backflow leak proof membrane cartridges. 100% Medical Grade Plastic jacket specially designed for holding more Ink, and to give consistent out flow of Ink. Each box of 20 Pcs. All cartridge needles are pre-sterilized, individual packed in blister pack ,disposable use only. The cartridge needles are compatible with various kinds of rotary machine pen. Safety membrane inside cartridges system, that stops ink from passing through to the tube or machine.