Solid state relay is a non-contact on-off electronic , is a four-terminal active device, two terminals are terminal, the other ends are output control terminal, it has optical isolation in the middle of them. Add DC or pulse to the input terminal, the output terminal's state can be changed from off to on (If there is , it is ), so as to control bigger load. Features - Color: Assorted color. - Material: Plastic, metal. - Size: 5.70X4.50X3.00cm/2.24X1.77X1.18 inch. - Output current: 40A. - Control voltage: 3-32VDC. - On-state buck: <=1.6V. - Control current: 5-20mA. - Load voltage: 20-480VAC. - On-off time: <=10mS. - Sealed high temperature resistance housing and transparent protective cap. - Non-contact, sparkless, noiseless, long lifespan. Widely used in many automatic control systems. - Mainly used for 3d printer hot bed, industrial automation devices, home appliance replacement like dust collector. - It is suitable for the environment with high requirements such as humidity, corrosion and ash. - And the occasion of frequent switching. Anti- , replacing electromechanical relay. Package list: 3 x relay