The DC Motor Speed Controller allows controlling speed of a DC motor using a Pulse-Width-Modulated (PWM) DC voltage with a Duty Cycle fully adjustable from 10%-100%. 
The motor speed controller can provide a continuous current of 8A to your DC motor or other DC load. 
The circuit also includes a 10A fuse, with reverse connection of power supply and control voltage over-voltage protection function. 

Specifications: 
Input supply voltage: DC 12V-40V 
The maximum output power: 400W 
The maximum continuous output current: 8A 
The overload and short circuit protecting current is 10A 
Static Current: 0.02 A ( Standby ) 
PWM frequency: 13kHz 
Duty Cycle adjustable: 10%-100% 
The operation environment temperature: -20 C-40 C 
The 10A fuse with reverse connection of power supply and control voltage over-voltage protection function 
(LxWxH): 6cm x 5.5cm x 2.8cm (approx) 
Net weight: 69g 

Note :
This can NOT be used to the BRUSHLESS motor. 
The controller is NOT reverse-polarity protected and will be damaged if connect the supply voltage with wrong polarity. 
Double check all connections before applying power and always turn off the power supply before making any wiring changes.