Abstract: A door stop formed of a suction cup attached to body, typically formed of a block of material such as clear plastic, which may be used to lock sliding glass doors and windows in either a closed or in a partially open position. The suction cup will hold to the glass for up to 3 months and dual suction plugs may be used for added security. The body is designed to tip and press the suction cup down to prevent sliding and thereby hold the stop assembly in place even when a strong horizontal force is applied. The body contains an alarm to discourage intruders in the event that the stop is dislodged from the door.