2.5'' LCD Digital Door Peep hole Viewer Security Camera NEW Digital 2.5 inch w/ LCD TFT Peep Hole Electronic Door PeepHole Viewer for Home Security Camera Simple one button operation,Zoom in with this digital peephole viewer Barrel will fit doors that are 35-57mm ,PowerSource: 2 AA batteries ( good for approx.1700 "peeps" ) Peephole: View Angle: 150 degrees,Size: Approx 146 x 90 x 30 It work if attached to a peephole in door. optical system tuned to peephole optics.