Rounded, streamlined case requires minimal chiseling during fitting. Installation spikes designed to mark drilling points for quick and easy installation (patent pending). Tough 22mm saw-resistant and drill-resistant bolt. Anti-jimmy hook bolt design to lock the door into the frame. Cylinder above lever configuration combines high security with ease of access. Follower incorporates a spindle grip to avoid loose spindles after fitting. Adjustable follower springing allows the use of either sprung or heavy unsprung furniture (patent pending). Robust drill-resistant case. Unique deadlocking latch provides the additional security of two-point locking (patent pending). Conform to the highest security grade within European Standard EN12209 and carry the CE mark for use on fire door applications.The Viper Deadlock kit (including BS3621 Lockcase, BS3621 Chubb 6 pin Cylinder, Escutcheons and fittings)