Surface-mounted security deadbolt, model crr10, made of steel with a satin brass finish, 86b/50 mm, with 5 keys and chain, 86 mm plate and 50 mm round cylinder, designed to reinforce security by installing on any type of door. its reversible design eliminates handedness - internal operation is via a button, while external operation is via a security key through the cylinder. it also features a cylinder protector and anti-bumping system