[Easy to Use ]We have made transmitter and receiver working together and test it before ship it,when you get it don't need to do anything ,just install it.[Widely Use]This remote switch used in industrial control and security fields, such as light, motor, remote controller, wireless security alarm, windows,lifting equipment, electric doors, wireless door alarm,security industry machine , wireless controller, and other fields[Signal]Wireless RF signal can pass through walls, floors, doors or windows. You can use two or more units in the same place. You can turn on/ off the receiver with transmitter from any place within a reliable distance(Max range is up to 164ft/50m with no obstacle).[Learning code] the Learning code has high-level security for its low repetitive rate and re-learn mode, it can delete the old code and re-learn a code,when a remote control get lost,So you could always control of it. Buttons: 2 ButtonsRemote Distance: 20-50MWorking frequency: 433mhzMax load current: 30AEncode: Fixed code / EV1527 codeDue to different batches, there may be differences in product appearance and printed text, which will not affect useColour:BlackMaterial:ABS Package Contents:2 x Remote Switch4 x Remote Controls 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 picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.