This radio transmitter Yokis E4BPP 4 channels is a radio transmitter to be placed behind a switch in the installation box. With 4 independent son, it will allow you to control 4 different devices. This Yokid E4BPP radio box can also control the shutters with double push button. Performance: Range of radio: 250m free view Frequency: 2.4Ghz bi-directional Transmitter potential-free contact (allows multiple applications) Maximum 4 receivers per channel transmitter in the same room with a 7 year battery life on a CR2032 Packaging : Yokis Radio Transmitter comes in its original packaging. Warranty: All Yokis brand products are guaranteed for 5 years from the date of purchase.