You know it, you need it - PACT Club Timer III

For training and measuring your performance, you need this timer. Well designed (with one minor exception), and easy to use, this is an essential piece of equipment for improving your draw, sighting your targets, and hitting your mark. The timer fits nicely on your belt, and is easy to read.

The controls aren't all intuitive, particularly switching between instant and delay, but once you know how, it's not a big deal. It's also a little tricky opening the battery door, because there's no ledge molded into the catch.