This is a 120 volt Westcott screw-in Studio Slave Strobe for the TD3 or TD5 light fixtures.
Use this strobes, when the tungsten or fluorescent lights for the TD3 or TD5 fixture just aren't enough. It has a built-in slave, and Guide Number of 72. It has a flash duration of 1/1000 second, 5800° Kelvin.
Compact, self contained slave flash.