When I say "installed" I'm using the term pretty loosely. The device is a free standing box which has a wire with a NATO plug coming out which plugs into the headset socket and a socket to plug in your own headset. CD and phone plugs into a side socket on the device. No "installation" said to be needed beyond that.. .. .Trouble is it causes ?feedback when any transmit buttons pressed. I sent the manufacturer a diagram of my wiring and he says it is standard R22 wiring. But on another occassion said that Robbies have some odd wiring compared to other aircraft. Something to do with the way they use part of the radio as the intercom between pilot and Pax.. .. .Leaves me still unable to use the box.