This is a very well-built compact darkroom timer that was tested and works perfectly. The Time-O-Lite was made in the USA by the Industrial Timer Corporation.
Though it's primarily intended for darkroom use (it has enlarger and safelight outlets) it can also be used a repeatable timer for other uses. This is the later iteration of the Time-0-Lite featuring grounded 3-prong outlets.
One nice feature is that the timer's face is glow-in-the-dark (don't worry, it's far too dim to fog paper); this is particularly handy for color darkroom work which must be done without a safelight.