 By 2004, shot clocks were available with a perimeter light strip around the clock that also lit up when the clock read 00.0.Today, the see-through shot clock units from Daktronics and OES have implemented the light strips that surround the shot clock that are turned on upon the clock registering 0.0.In recent years, timekeeping rules have changed with the implementation of a system where the blowing of an official's whistle stops the clock at the instant of the whistle, along with a rule change where the on-court official (not an official at the scorer's table) starts the clock by pressing a button attached to the official's belt.