Trisponder 540 Digital Distance Measuring Unit, by Del Norte Technology. Item has a yellow shell and black fascia with square power push button on top left. Left side of object front is LCD screen. Right side is a touchpad with numbers 0 to 9 and north, east, south, west buttons. Other buttons are change screen, "." button and escape, cancel, accept, clear buttons. There is a seperate display intensity touchpad with up or down buttons. The outputs at the back of the console are BCD, external update, DMU com line, seial out, remote video, transponder, power in.