US Patent 8230645 Adjustable removable restraining stop for double hung windows

An adjustable restraining stop assembly permits a residential double hung window to be locked in a partially opened position to permit ventilation through the partial opening. The stop assembly includes an outer tube with a telescoping inner tube. The outer tube is mounted to a window sash by a removable fixation device, such as a mounting hook and loop arrangement. A convenience knob is attached near the distal end of the inner tube. Adjustment is set by placing a desired hole of a plurality of holes in the telescoping inner tube in registration with a single hole in the outer tube and then inserting the end of a fastener, such as a cotter pin, locking both tubes together.