Viscount 5 Lever High Security Sashlocks are recommended for use in timber or composite doors. Two hardened steel rollers in the bolt help to resist hacksaw attack. The 5 Lever mechanism is designed to prevent lock picking.The latch bolt can be easily reversed for left or right handed doors. ERA Viscount locks are ideal for use in new doors or upgrading security from 2 and 3 lever door locks. Sashlocks are for use with door handles.