Trimco 3921-8 Heavy-duty Surface Bolt 8" long with Decorative Knob

Four standard lengths: 8, 12, 18 and 24 inches. The length is the bolt body, so pick it by how far you need to reach from the knob position to the head or the sill. On a pair of doors, an 8 inch bolt is the usual short throw at the top rail, while the 18 and 24 inch versions are what you use when the bolt has to run up a tall stile to reach the head. All four lengths are offered in every finish carried: 605 bright brass, 606 satin brass, 613 oil rubbed bronze, 625 bright chrome and 626 satin chrome.

A surface bolt like the Trimco 3921 mounts on the face of the door and is a good choice when you want the inactive leaf secured and you can accept visible hardware. It installs without mortising the door edge, which matters on existing doors and on wood or glass-front openings you do not want to cut into. Flush bolts are the alternative when the specification calls for concealed hardware and you can mortise the door edge. The 3921 is a heavy duty commercial bolt with a decorative knob, so it is aimed at openings where the hardware is seen and the look matters as much as the hold.

The 3921 Series is offered with multiple strike options, so the strike is a choice you make when ordering rather than a single fixed part. Which one you need depends on where the bolt lands: a bolt shooting into the head of the frame, into a threshold or floor, or into the edge of the adjacent leaf all want different strikes. Decide the mounting location first, then specify the matching strike with the bolt.

Solid bronze or brass construction, rated by Trimco as heavy duty and built for commercial use. That is the reason it goes on office buildings, hospitality, multifamily and mixed-use, government and military facilities, and commercial and industrial buildings. Solid brass or bronze also means the plated finishes are on solid metal rather than a stamped shell, which is what a property manager cares about on a door that gets worked every day.

Five BHMA finish codes are carried on the 3921: 605 bright brass, 606 satin brass, 613 oil rubbed bronze, 625 bright chrome and 626 satin chrome. Those are the same codes stamped on levers, hinges and closers, so match the number rather than the name. If the building is standardized on 626 satin chrome, which is the common commercial default, the bolt is available in 626 in all four lengths.

Custom options are available on the 3921 Series beyond the 8, 12, 18 and 24 inch standard lengths. That is the route when a tall door or an unusual stile height means none of the stock lengths reaches the strike. For anything stock, one of the four standard lengths in any of the five finishes will cover it.