Specifically designed as a top security lock for sliding glass doors. The exclusive Keymatic Cylinder allows combination changes using the Keymatic Master Combination Key. Up to eight different keys may be used to operate the Lock. Installs with only a screwdriver. Maximum door thickness is 1/4" (6 mm) with the standard bar. An Optional Adjustable Bar allows use on doors up to 1/2" (12 mm) thick. The front shoulder on the lock barrel prevents spreading of glass panels to bypass the Lock.