The Crankbrothers Sterling CO2 inflator is Crankbrothers uber quality version of a cycling staple. The head is very well made with a die cast zinc body and trp cover. Air enters the tube via a spring-controlled push valve so you basically just thread in the CO2 cartridge and no air is released until the head is pressed against the (open) valve stem. There is an integrated frost guard that keeps your fingers from freezing when the air is released. Two CO2 cartridges are included.