This versatile and simple to use millisecond timer offers a convenient way to measure time durations of 0- 9.999 s. It has built in logic to allow A - A and A - B timing modes using the two inputs provided. The millisecond timer automatically adjusts for normally open and normally closed switches making set-up very simple. The millisecond timer is a perfect choice for use with the g by freefall apparatus, Unilab light gates and other fast timing applications.