This is a Traxxas XL-1 Electronic Speed Control with Reverse.  This speed control handles 17-Turn and above motors.  This is a good, inexpensive way to upgrade from a mechanical speed control.

Features
Fully proportional forward and reverse.
Radio connectors are Futaba J style.
Battery connector is Tamiya.
Motor connectors are bullet type.
Has reverse, heatsink, LED indicator and uses MOSFET.
Warranty is 30-Day.
ON/OFF switch.

Includes:
One XL-1 Traxxas Speed Control w/Reverse.

Specs
Cells: 4-7
Amps Continuous: 75
Amps Peak: 100
Voltage Drop: 0.019
Weight: 3.4oz
Dimensions including heatsinks:
2.4" long x 1.5" wide x 1.4" high