Locking and unlocking from inside: with turn handle. The safe-T-catch locked from inside can be unlocked from outside via cylinder key. G.U-SECURY Automaticwith safe-T-catch G.U-SECURY MR 2with safe-T-catch G.U-SECURY MR/Rwith safe-T-catch G.U-SECURY SH 2with safe-T-catch Advantages: No face fixed lock and no chains either! Integrated one way door opening restrictor system with convenient operation via turn knob and door lock cylinder. Security locking prevents accidental opening. Suitable for DIN left and DIN right hand doors. Versions for all current timber sections available. Profile related versions for PVC and aluminium doors. Ideally suitable for entrance doors of one-family houses and for flat entrance doors