LOX: Lox is short for liquid oxygen and is cryogenic with a freezing point of 50.5 K (−368.77 °F; −222.65 °C). A liquid oxygen system comes standard with a mother and a portable tank/stroller that the oxygen user can fill with oxygen from the tank. There are two different types of systems, top fill and side fill. (see other pages in this site). LOX is, next to a portable concentrator (POC) the preferred system for people who continually use oxygen and still want to be mobile. Liquid oxygen evaporates slowly from the vessel and from the portable and cannot be stored indefinitely.