Features: 
Circuit board using military grade sheet. 
All the chips are used imported. 
With Imported 50V 1000uF large capacitor. 
Power tube using IRF3205 this bull,no worry about your motor not moving.(parameter drain current Id Max: 82A; voltage Vds Max: 75V; open state resistor, Rds (on): 0.013ohm). 
Terminals use 8500 large current terminals, labeled 300V 20A. 

Specifications: 
Potentiometer resistance: B100K 
Openings: 8mm 
Working power: DC12-V40V 
Power control: 12V*8A=96W ,24V*8A=192W,40V*8A=320W 
Rated current: 8A 
Maximum current: 10A 
Speed range: 10%-100% 
PWM Frequency: 13KHZ 
Product size: approx. 60*55*28mm/2.36*2.16*1.1'' 
Net weight: approx. 68g 

Note:  
1. DC motor speed control input is DC, can not directly connect AC current (such as the 220V AC) otherwise it will burn. 
2. The positive and negative poles of the DC power supply can not be reversed, Otherwise the governor will damage. 
3. Motor can be divided into positive and negative, when the direction of operation and expectations are inconsistent, you can change the direction of the alignment. 
4. The potentiometer knob can change the output duty cycle of the governor, thus changing the speed of the motor. 
5. Please allow 1-3mm differs due to manual measurement. 
6. Due to the different display and different light, the picture may not reflect the actual color of the item. Thanks for your understanding.