Deltana 3BB 3" Solid Brass Barrel Bolt with Matching Screws

That's exactly how a barrel bolt is meant to be used. The 3BB mounts on the inside face of the door, separate from any lockset, and throws a solid brass bolt into a strike or keeper on the jamb. It's secondary security you engage from inside when the main lock isn't doing the work, so it doesn't interfere with existing bore holes or the latch prep. No key, no cylinder, no outside operation.

The 3BB measures 3 inches, which is the plate length that names the model. That's the small end of Deltana's barrel bolt range and it suits interior applications where you want privacy and a positive stop rather than forced-entry resistance: bathroom and bedroom doors, closets, a French door leaf, a gate. On a heavy exterior entry that takes real abuse, step up to a longer barrel bolt so more of the bolt engages the jamb.

Solid brass, both the material and the substrate. That matters on a surface-mounted part, because the bolt and barrel take the wear directly and there's no housing hiding them. A plated zinc bolt wears at the throw point and shows the base metal; brass through the section doesn't. The screws packed with it are solid brass as well, so the fasteners age with the bolt instead of rusting out ahead of it.

Screws come in the box. Each 3BB is packed as one barrel bolt with matching solid brass screws, sold by the each, so the price you see covers a single complete bolt. Order one per door leaf you're securing, and remember a pair of doors that meet in the middle typically wants a bolt on the inactive leaf top and bottom, which is two units on that opening.

Nine finishes: polished brass, PVD polished brass, antique brass, polished chrome, brushed chrome, brushed nickel, antique nickel, oil rubbed bronze, and paint black. If you're matching a fleet of openings, PVD polished brass is the one to specify where the bolt sees hands or weather, since the PVD coating holds its color where a lacquered polished brass will eventually break down. Oil rubbed bronze is a living finish and will darken and wear at the throw point over time, which is normal for it.

Deltana classes the 3BB as commercial. In practice that means it holds up in a multi-family or hospitality setting on the kind of opening a barrel bolt belongs on, secondary privacy and hold-open duty. It is not a substitute for a Grade 1 deadbolt or an exit device on an egress door, and surface bolts on a required egress opening are governed by your local code, so a facility spec should be checked against that before you standardize on them.

Handing is not a factor with either, but the mounting is. The 3BB is a surface bolt, it screws onto the face of the door and sits proud of it, so installation is fast and needs no mortising, but the hardware is visible and the bolt can be knocked. A flush bolt is mortised into the edge of the door and disappears when retracted, which is the cleaner look on a nice pair of doors and the usual choice on a fire-rated pair. If you're retrofitting existing doors with hand tools, the surface-mounted barrel bolt is the practical answer.

The 3BB is a wood-door part in practice. It fastens with the solid brass wood screws it's packed with, into the face of the door, so it needs solid material to bite into. A hollow metal door needs the holes drilled and tapped or through-bolted with your own machine screws, and a glass front aluminum stile has neither the substrate nor the face width for a surface bolt like this. For an aluminum storefront pair, look at a flush bolt or a two-point device built for the stile instead.

One unit is one bolt. The 3BB is sold each, packed as a single barrel bolt with its screws, so the count is straightforward: one per bolt location, not per door. Property managers doing a floor of bathroom or unit doors should count locations rather than doors, and order the same finish across the run so the openings match.

Brass throughout is what makes that viable. The 3BB body and its screws are solid brass, which won't rust the way a plated steel bolt does on an exterior gate, and there's no cylinder or spring pack to seize. Two cautions for outdoor use: a 3 inch bolt is short, so on a gate that racks or swells you want the keeper set with a little play, and unlacquered or living finishes will patina quickly in weather. PVD polished brass is the finish that holds its appearance outside.