The Extra Heavy Duty Surface Mount Overhead Stop & Holder is designed for correctional institutions and bank vault door applications. Interior or exterior use. For use on single acting, extra heavy weight doors with frequent traffic. Door can be mounted with hinges, offset pivots or center hung. Shock absorbing spring provides a 3 to 5 degree cushion before a dead-stop. Standard installation from 85 to 110 degrees of opening (5 degree increments). Standard fasteners supplied with sex bolts for 1-3/4" to 2" thick doors.