1,Stepless speed control with silicon controlled trigger 2, the introduction of negative voltage feedback technology to make the speed more stable 3, with over-current protection cut-off device to make the performance more 4, with displacement to achieve automatic stepless speed regulation 5,With photoelectric switch to achieve long-distance control With soft device to eliminate the motor starting current is too larg Input voltage: AC220V10%, 50/60Hz Output current: 3.5A Static accuracy: 5% Adapted motor power: 50~500W Armature output voltage: DC0~220V Excitation output voltage: DC200V/1A Colour:As Shown Material:PCB Package Contents: 1 x speed control board Only the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing.The measurement allowed error is +/- 1-3cm.