Exceeds ANSI Grade 1 standard for auxiliary locks. Solid brass, free turning collar and 1/4 inch diameter mounting bolts resist wrenching, prying and hammering attacks. 1 inch throw hardened steel bolt resists sawing and crowbar attacks. Hardened steel inserts and rotating pins provide drill and pick resistance according to UL 437 standard. The Biaxial® design offers a utility patent that provides protection against unauthorized key duplication. Large thumbturn provides ease of use by physically challenged individuals. Steel shroud over bolt protects against "ice pick? type attacks. High security strike plate has a special box design with 2? screws that anchor the strike directly to the building structure behind the frame, preventing "kick-in? type attacks. Hardened steel bolt and bolt throwing mechanism are surrounded by a heavy-gauge tubular steel housing for maximum resistance to crowbar attacks. Solid brass design is secured with high-tensile steel mounting bolts for maximum resistance against hammer and prying attacks. Utility patented key control, (for cylinders that incorporate the Biaxial design), provides protection against the unauthorized duplication of keys. A special elevating and rotating pin tumbler design, along with false slots on the bottom pins, mushroom top pins and a sidebar mechanism, work together, to provide superior pick resistance. Angled cuts on the keys, along with fore and aft positioning, in the Biaxial design, provide added dimensions that dramatically increases key combinations. Hardened steel inserts, positioned in critical areas of the cylinder, provide a high degree of drill resistance. UL437 listing provides assurance that cylinders meet universal standards for drill and pick resistance and resistance against other types of forced attack. Requiers 2-1/8" diameter hole.