Wikipedia
ATNAA
An ATNAA ( Antidote Treatment Nerve agent autoinjector) is any of a variety of autoinjectors in use with the US Armed Forces. An autoinjector (or auto-injector) is a medical device designed to deliver a single dose of a particular (typically life-saving) drug.
Most autoinjectors are spring-loaded syringes. By design, autoinjectors are easy to use and are intended for self-administration by patients. The site of injection depends on the drug loaded, but it typically is administered into the thigh or the buttocks. The injectors were initially designed to overcome the hesitation associated with self-administration of the needle-based drug delivery device. It is the newer delivery vehicle to be used in lieu of the Mark I NAAK.