This KC2300 series cylindrical commercial door knob is tested to ANSI A156.2 Grade 2 is tested to last over 400,000 cycles. A cylindrical chassis allows the wear to be on the mechanical body and not the latch for a longer lasting lever. This commercial heavy duty knob is best for heavy traffic areas and has a best in class 3 hour UL rating and can be used on fire doors. Round ball knob comes with a square T strike and limited lifetime warranty. This satin chrome passage knob does not lock. It can be used on hallway or closet doors in offices, schools, hospitals, apartments, hotels, and motels. Easy installation with a 2 3/4" backset that fits standard door prep.. Tell Manufacturing provides a full line of commercial products including commercial grade levers, commercial grade door knobs, commercial grade deadbolts, closers and exit devices, hinges, and assorted builders hardware. They offer cylindrical or tubular door hardware and entrway door locks. Cylindrical locks have a chassis or mechanical body instead of a spindle. The latch bolt for cylindrical locks only goes through the lock bore partially and connects to the chassis of the lock. Some cylindrical locks have thru bolts that help secure the lock to the door. Due to the mechanical construction of a cylindrical lock it makes them heavier duty than the light duty. Tubular locks have two different pieces, the outside and the inside trim. The latch bolt for this style is continuous and goes all the way through the mounting hole or bore in the door. When installing the lock the spindle then goes through the latch. Tubular locks are considered to be light duty. All Tell levers are ADA compliant designed in a manner that is easily operated by those with disabilities, including lever size, projection from the door, etc. Door hardware includes double cylinder deadbolts and single cylinder deadbolts, levers, and knobs. Levers and knobs are offered in multiple functions including keyed, passage, privacy, and storeroom.