Abstract: A 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 in each side of front panel of a first frame member and the opening is spaced inwardly from the outer edge of the panel so as to communicate with the door opening. A narrow elongated quadrilateral integral flange extends along and projects rearwardly toward the door from an outer edge of each front panel. A second narrow elongated quadrilateral and generally L-shaped integral flange extends along the inner edge of each front panel with each L-shaped flange comprising first and second panels.