Lockwood Deadlock 355-NMBKDP Double Cylinder Deadlock designed to offer high security level commonly used in commercial and domestic applications. Double Cylinder Deadlock Function - opened by key from outside and by turn knob from inside when free. Internal key locks or unlocks turn knob. The premium security features provided by the 355 Deadlock make it an ideal lockset for both domestic and commercial applications. Suitable for hinged and some sliding doors. Features: Lockable internal turn knob with inbuilt clutching device Strong interlocking case and mounting plate to resist jemmy and hammer attack Concealed fixing Positive deadlocking action Internal and external 5 pin tumbler mechanism Compatible with most restricted keying systems Supplied boxed with 2 keys Specifications: Door Thickness: 35mm - 45mm Body / Case Material: Zinc Bolt Material: Stainless Steel Number of Cylinders: 2 Backset: 60mm Handing: Reversible Approved Standards Rating Level: Lockset Security SL7, Corrosion Security C6, Durability D8 Bolt Holdback: Yes Kinetic Defence: Yes Finish: Matt Black