The ‘g’ by Freefall apparatus consists of an electromagnet housed in a plastic moulded case supplied with a heavy steel sphere, an electromagnet unit with connections for an external timer and a platform unit containing a microswitch and terminals for the external timer.

The sphere is released by moving the switch on the electromagnet to the upward position, which starts the timer. As the sphere hits the cork mat on the platform unit, the lid moves down and activates the microswitch to turn off the timer. For use with timer unit NS3301.