This Linear DR-2 / DNR00018 is a 2 channel 310 MHz radio frequency replacement garage door radio receiver. This unit is perfect for an application where you may have 2 older garage door openers that you want to be able to utilize a dual button remote control on. Installation is simple you can either mount the unit directly on to the opener if your old opener has 3 screw terminals on the back of it. Or you could remotely mount the unit and run a wire to the openers you wish to control. Then set the 8 on/off dip swtiches on the remtoe control(s) and your ready to go.