The 4510T Smoothee Series is a heavy duty, high security closer with special components to minimize tampering and vandalism. Forged steel single lever arms and heavy gauge metal security covers are designed for correctional, vandal prone, institutional and other high traffic applications. Sized cylinder for 26" interior doors. Features include a cast iron body, full complement bearing, 1-1/2" diameter piston, 11/16" diameter double heat treated pinion journal. Solid forged steel, large cross section arm. Special threaded attachment of track roller for potentially abusive installations. Double slab arm/pinion attachment for maximum strength.