Abstract: An improved tamper-proof window unit comprising similar first and second quadrilateral centrally open frame members adapted to be mounted about an opening respectively on opposite sides of a door. Each frame member has a narrow elongated quadrilateral front panel extending generally in a plane parallel to the door and marginally about the door opening with an outer edge portion partially overlapping the door adjacent the opening. A small countersunk front-to-rear screw hole is provided on each side of the front panel to communicate with the door opening. A narrow elongated quadrilateral and generally L-shaped integral flange extends along the front panel with each L-shaped flange comprising first and second panels. The first panel of each flange projects generally rearwardly and the second panel projects from the rear edge of the first panel outwardly with respect to the door opening.