For 1-in minimum doors weighing up to 150 lbs. Precision ball bearing wheels ensure smooth, quiet, and long lasting performance. Pre-drilled aluminum box track hides the hardware. Spring loaded quick release mechanism for easy door installation and adjustment. Has 2-in (12.7 mm) vertical adjustment; minimal headroom required. Needs 2-1/16-in (52.4mm) minimum headroom. Offers 2-9/16-in (65.1 mm) maximum headroom. By-pass applications can be achieved by mounting two tracks in parallel. Bi-parting applications achieved by adding an additional 150E hardware set.