Kaba Ilco FLB Series Flush Bolt

That's exactly the opening the FLB Series is built for. It secures the inactive leaf of a pair of doors, and it's sold as a retrofit part, so it goes into existing openings rather than needing new prep. Pick the offset that matches the gap between your bolt housing and the strike point: 1/4 inch, 3/16 inch, or 1/8 inch. Throw is either 5/8 inch (15.87 mm) or 7/8 inch (22.23 mm), so you match the throw to how deep the bolt has to reach into the head or threshold.

Offset is the sideways step between the bolt body and the rod tip, and it has to match the geometry of the door and frame you're bolting into. The FLB Series comes in three: 1/4 inch (6.35 mm), 3/16 inch (4.76 mm), and 1/8 inch (3.18 mm). Measure the offset on the bolt you're pulling out, or measure from the bolt centerline to the hole in the head or threshold, then order that number. Every one of the three offsets is available in both throws and in both finishes.

Yes, and this is the practical reason to use it on a retrofit. The rod length adjusts by turning the nylon tip, so you can dial in engagement on site instead of shimming the frame or drilling deeper. Between that adjustment and the choice of 5/8 inch or 7/8 inch throw, you can usually land it on an existing hole.

The longer 7/8 inch (22.23 mm) throw buys you more engagement, which matters when the head channel or threshold hole is deep, when the door has settled, or when there's a wide gap at the top of a storefront pair. The 5/8 inch (15.87 mm) throw is the shallower option and is what you match when you're replacing a bolt that already engages fine and you don't want to change the hole. Both throws are offered in all three offsets and in both Aluminum and Dark Bronze.

The standard rod is zinc plated steel with a nylon tip. A metal tip version exists as a special order, and it is fixed at one configuration: 1/8 inch (3.18 mm) offset with 5/8 inch (15.87 mm) throw. So if your opening needs a 1/4 inch or 3/16 inch offset, or the deeper 7/8 inch throw, the nylon tip is the one that fits. Keep in mind the nylon tip is also what you turn to adjust rod length.

Count by bolt location, not by door. A flush bolt secures the inactive leaf at one point, so a pair bolted top and bottom takes two, and a pair held only at the head takes one. Order the same offset and throw for each position only if the head and threshold conditions actually match; if the top gap and the threshold hole are different, they can take different offsets. The FLB is sold as single configurations across three offsets (1/4, 3/16, 1/8 inch) and two throws (5/8 and 7/8 inch), so mixing is straightforward.

A flush bolt like the FLB Series sits in the edge of the door so nothing protrudes into the opening, which keeps the active leaf swinging clean and looks finished on a storefront. A surface bolt mounts on the face and is easier to add with no mortise, but it's visible and it can catch. The FLB is aimed at the retrofit case: it drops into an existing inactive leaf, and the nylon tip turns to adjust rod length so you can match the hole already in your head channel or threshold.

Two: Aluminum and Dark Bronze. Those are the two finishes that cover most commercial aluminum entrances, so a property manager standardizing across a building can match clear anodized or dark bronze frames without a special order. Both finishes are available across all three offsets and both throw lengths, so the finish choice never limits the fit.

Commercial. The FLB Series is a commercial door hardware item, built for the inactive leaf of a double door in a storefront or commercial entrance rather than for residential French doors. The rod is zinc plated steel.