As a sinusoidal or three-channel receiver, the 850Ll can control up to 3 doors or garage door openers.CH1.50 remotes and 2 keyboards. CH2:20 remote control and 2 keyboards. CH3:20 remote control and 2 keyboards. The 850LM receiver can also be used with a 3-key remote control to operate the opening, closing and stop functions of the commercial door operator. Remote/keyboard control: default 315 MHz, remote control model: 811LM, 811LMX, 813LM, 813LMX, 891LM, 893LM, 890MAX, , 892LT, 894LT. Keyboard control: Model 877LM, 878MAX. If the receiver changes from the default 315 MHz to 390 MHz, the compatible remote controls are: 811LMX.813LMX .892LT and 894LT. Compatible keyboard is 878MAX Antenna expansion kit: Model 86LM, 86LMT, antenna only: K77-36541 Please note: the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! Colour:As Shown Material:Metal+Plastic Package Contents: 1 * garage door receiver 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.