The CRL Chrome Track Plunger Lock installs easily in track assemblies with sliding glass doors. You can install it in either the top or bottom of the door. The spring-activated design permits locking simply by pushing the plunger without the key. Comes with ferrule and two keys. If the 981 is used with Cat. No.'s D610, D5610 or MC610 'H' Bar, the glass will require notching. If the LK610 'H' Bar is used, no notching of the glass is required. For replacement Keys order Cat. No. 981KEY.