The Blackwing Pen's hefty click is the result of a dual-spring click mechanism that was designed to be click, click, clicked. Its machined aluminum body features a unique “half moon” shape that is comfortable to grip and ensures your pen doesn’t roll off your desk. Each black ink pen includes a medium Schmidt rollerball cartridge that lays down a smooth, expressive line, but it will work with any cap-less rollerball pen cartridge.