Trimco 3820 Semi-Automatic Flush Bolt, Metal Door, OA (Overall Size) 1 x 6-3/4"

The 3820 is the metal door version of Trimco's 3800 Series semi-automatic flush bolt. The 3800 Series is built in separate metal door and wood door versions, so if the inactive leaf is a hollow metal or steel door, the 3820 is the one to order. On a wood inactive leaf you need the wood door model instead, not this one.

Plan the pocket around a body of 6-3/4 x 1 x 1-1/2 inches. The face plate covers 1 x 6-3/4 inches overall, and the separate bolt guide that mortises into the top or bottom edge of the door measures 2 x 1 x 1/16 inches. Those are the two preps: the body pocket in the door edge at the lock height and the guide at the door edge where the bolt lands.

Yes, and it isn't part of the flush bolt. The 3820 ships as the bolt body plus its 2 x 1 x 1/16 inch guide for the door edge. Where the bolt lands, in the frame head or in the floor or threshold, you need a matching strike or dust proof strike ordered separately. Get that prep decided before the frame goes in.

The bolt itself is not handed, but the count is. A pair of doors normally takes two flush bolts in the inactive leaf, one at the top into the frame head and one at the bottom into the floor or threshold. On a fire rated pair both are typically required. The 3820 is sized 6-3/4 x 1 x 1-1/2 inches per bolt, so order two of them for one full pair.

Both live in the inactive leaf of a pair and both release automatically when the active leaf opens, so the inactive door can swing without anyone reaching for the bolt. The difference is at reset: an automatic bolt throws itself when the doors close, while a semi-automatic like the 3820 needs the bolt pushed back into the throw position by hand. Trimco builds the 3800 Series both ways, so if you want a truly hands-free pair, specify the automatic model; if you want the inactive leaf to stay released until someone deliberately secures it, the semi-automatic is the one.

That's the failure mode the 3800 Series design targets. Trimco's patented mechanism needs very low closing force to secure the door and runs quiet, and it uses about a third fewer parts than competing flush bolts, with stainless steel in the key components. Fewer moving parts and low actuating force is what keeps a bolt working in corridors, hospitality suites, multifamily and office openings where the pair cycles hard all day.

Square. The 3820 uses a square bolt, so the strike or dust proof strike you pair with it needs a square opening to match. A round bolt strike will not seat it correctly.

Satin chrome / satin stainless steel is the finish offered on the 3820. Key parts of the bolt are stainless steel construction, which is why the exposed face reads as satin stainless rather than a plated finish, and it sits alongside typical satin stainless lever and push plate hardware on a commercial opening.

Yes. The 3800 Series uses interchangeable trim kits, so the visible face trim can be swapped to match a finish change or a hardware standard across a building without pulling the bolt body out of the door mortise. That matters to a property manager standardizing openings across a portfolio one phase at a time.