Very nice item. It provides an accurate control of the velocity of a DC motor. It would be nice to have a small improvement : - to make that on-off incorporated switch also switches the entire regulator (turning off the display, also) and not only interrupting the motor's current. Other good idea would be having a way to place the device on a surface, instead of only intended dashboard mounting.
Online store: AliExpress
US $2.37 5% OFF|DC 5 30V 12v 24v 5A DC Motor Controller PWM Adjustable Speed Digital display encoder duty ratio frequency MAX15A-in Signal Generators from Tools on AliExpress
2.37 USD