Electronic Speed Controllers (ESC) for Radio control Airplanes, helicopters, Cars, tanks, Boats, robots, Drones and test rigs.
These units regulate power to the motor most of the units also supply power to the receiver (this is called a BEC) an "Opto" Esc does not supply power to the reciver.
There are two types of ESC Brushed (2 wired motor) and Brushless (3 wired motor)

Electrospeed
Electrospeed Motor & ESC Boost 40 Power Pack for use with VQ models and similar
$74.43
Re-stocking soon