16 VAC 40 VA Plug in wall transformer with internal self-resettable fuse. Screw terminals, two for AC output and one for connection to ground. If the output of the unit becomes shorted with this transformer, you don't have to throw it away like many other fused units as it will self-reset once the short circuit is resolved. 16 VAC for use with many access control systems (Integra32) and some types of electric strikes. Has muted green power light indicator on the back. Screw tab for screwing the unit into a duplex wall outlet for a semi-permanent installation.