Designed to be applied as the prehung door is being assembled, Jentra Tools’ Pro-Tect Plug aids in proper door assembly before packaging and shipping the prehung unit, says the company, by inserting the rubber door spacer between the door and frame to protect pre-finishing on painted and stained door systems. They also provide the door installer with the exact spacing the pre-hung was manufactured with. The plug is engineered to fit the edge of a 1 3/4-inch-thick prehung door and works on 2 3/8- and 2 3/4-inch backset bores.