Newly installed 4 channel enforcer wireless receiver and 1 channel receiver.
These wireless relays are used for door "buzzers"
a 4 channel FOB keychain is also shown in the image.
The network room has a metal ceiling, and there are 2 brick walls that the signal needs to pass to get to the front door, so an external antenna needed to be installed and mounted to get the signal to reach to the front door. Pulling a new wire and installing the single channel relay closer to the front door was NOT an option, because the building owner had a problem last time we tried pulling cable thru the common hallway of the building, not to mention, this is the location with the sheetrock ceilings, so it would have taken a day or 2 to even get that wire run.