1 piece of original Hörmann remote control / transmitter complete with battery and instructions. Type: HSM4 mini transmitter with green buttons. Frequency: 26.975 MHz. 4-channel (4 buttons for 4 functions / gate drives). Button color: green. Battery: 12V type 23A. Dimensions: 37 mm x 60 mm x 12 mm. Your old Hörmann remote must have the same button color as the new remote. It's that simple to find the right frequency: light blue buttons = 868.3 MHz (not compatible with series 3 - BiSecur!), gray buttons = 40.685 MHz, green buttons = 27 MHz (exactly 26.975 MHz). DIY series = 433 MHz RC (Ecostar). The frequency is also indicated on your Hörmann drive and on the back of the remote. If your drive is not from Hörmann, then these remotes will not fit. Please note that the new types of remotes, which are only specified with 868 MHz, are not available for the old frequencies of 40.685 MHz and 26.975 MHz.