Vintage Vanguard Model V-50 FT Mechanical Heat Detector /Fire Alarm

Vintage 1970's Vanguard Model V-50 FT Mechanical Heat Detector /Fire Alarm. Condition is very good. This is a mechanical heat/fire detector. Requires no battery or electricity. Includes mounting bracket and winding key. Alarm is wound, and the fuse is set in place. Temperature rising more than 1 degree per minute will activate alarm. Item will be shipped unwound.