Will this twist-lock light sensor work with a Regent (Cooper) 175 Watt Mercury Vapor light?

It should. Mine works with a 175W Sylvania Mercury Vapor bulb

This sensor is rated at a 1000 watts/130 volts. If your mounting prongs & voltage specs are the same, this sensor should work. Hope this helps. :-)

The sensor came with my original Mercury vapor security lamp assembly. When the bulb circuit (not the sensor) failed I could not get another replacement unit at the time and ended up switching to a sodium light unit which has really worked better. It uses the same sensor. Beware of the wattage and the voltage requirement. The sensor is a LDR (light dependent resistor) that controls the current through the heating element on the bi-metallic strip. Putting the 120vac sensor in a 277vac circuit will most likely destroy it while the reverse would not function properly.