Deltana EFB 12", 18", 24", and 39" Extension Flush Bolts, Solid Brass

An extension flush bolt mortises into the edge of the inactive leaf of a pair and throws a rod up into the frame head (or down into the threshold) to hold that leaf fixed, so the active leaf has something solid to latch against. The Deltana EFB uses a cam mechanism for the sliding open-close action rather than a spring, so there is no spring to break over time. The bolt body is solid brass with a stainless steel extension rod.

Four rod extensions: 12, 18, 24 and 39 inches. The length you need is driven by how far the bolt face sits from the head or the threshold. On a standard opening a 12 inch rod reaches the head from a normal top-of-door mount; longer rods exist because many people set the bolt down at a reachable height on a tall or oversized leaf, and the 39 inch is the one for reaching the head from roughly waist level. Measure from where you want the operating lever to sit to the point the rod has to enter, and order the rod that covers it.

Eleven finishes are offered on the EFB flush bolt: Antique Brass, Antique Nickel, Brushed Chrome, Brushed Nickel, Oil Rubbed Bronze, PVD Polished Brass, Paint Black, Polished Brass, Polished Chrome, Polished Nickel and Unlacquered Brass. That covers the usual Deltana finish families, so a property manager standardizing a building can carry the same finish across levers, hinges and flush bolts. PVD Polished Brass is the plated version that holds its color; Unlacquered Brass is bare and will patina.

Deltana rates the EFB extension flush bolt for commercial use. Solid brass body with a stainless steel rod and a cam action instead of a spring is the combination that holds up in a building with real traffic, which is what makes it workable on apartment entries, office double doors and similar openings rather than only interior residential pairs.

The EFB is sold each, priced per unit, so a top-and-bottom installation on one inactive leaf takes two. Some jobs only use a top bolt, with the active leaf's latch doing the rest. Order the quantity your opening calls for rather than assuming a set, and note that a top bolt reaching the head and a bottom bolt reaching the floor often need different rod lengths.

A standard flush bolt is a short self-contained unit mortised in at the very top and bottom edge of the leaf, which means reaching a ladder to operate the top one. An extension flush bolt puts the operating lever in a mortised face plate lower on the door edge and runs a long rod from there to the head. The Deltana EFB does that with a stainless steel rod in 12, 18, 24 or 39 inch lengths, so pick it when you want the bolt operable without a ladder or when the leaf is taller than standard.

There are none. Deltana's EFB uses a cam mechanism for the sliding open-close action specifically to eliminate springs that can break, which is the usual failure on a flush bolt that has been in a door for years. For an MRO or maintenance crew replacing bolts that have gone stiff or dead, that is the reason to move to this style.

Plan on the strikes separately. A top bolt needs a strike mortised into the frame head, and a bottom bolt needs either a floor strike or a dust proof strike set into the threshold or slab. The EFB itself is the brass bolt body and the stainless rod, mortised into the edge of the inactive leaf, so the routing for the face plate and the rod channel is the install work. Order the strike in the same finish family you picked for the bolt.

For an ordinary pair where one leaf stays fixed, a manual extension flush bolt like the Deltana EFB is the straightforward answer. Where the opening is an egress door, a manual flush bolt is usually the wrong device, because it requires a second action to release the inactive leaf; those openings normally take automatic or self-latching flush bolts, or vertical rod exit devices. Decide that against the code the opening is being inspected under before you order a manual bolt.

No handing to specify. The EFB is ordered by rod length (12, 18, 24 or 39 inch) and finish only. It mortises into the edge of the inactive leaf and throws straight up or down along that edge, so the same bolt works on either leaf of the pair regardless of swing.

The rod, which is the part that runs down into a floor strike where water collects, is stainless steel. The body is solid brass. Neither ferrous-rusts, so the EFB holds up better in a humid corridor, a pool building or a covered exterior pair than a plain steel bolt. Finish choice still matters outdoors: Unlacquered Brass will patina by design, while PVD Polished Brass is the plated finish that keeps its appearance.