I have a MrGr8ness rangefinder light kit i never used. It was made to fit the TF rangefinder, but will likely fit many others. the board is 1" X 7/8". It is made to be used with the micro switch. Comes with instructions how to hook it up. Runs on a 9volt battery, and a hollow stalk is needed to run the wires through.
$50 plus shipping.