Zero International 350A Sill Protection Automatic Door Bottom with Solid Neoprene Insert

That is what the 350A is built for. It has a maximum effective drop of 1 inch, and the concealed flat spring drops the neoprene seal in a scissor motion so it compresses tightly even against an uneven floor or saddle. If your undercut gap exceeds 1 inch at its worst point, the seal won't reach the floor there and you need a different bottom condition, not a longer stroke.

Mortised. The 350A housing sets into a routed pocket in the bottom edge of the door, so the door has to be prepped (or come prepped) for it. If you're retrofitting an existing door in place and can't pull it and mill the bottom edge, a surface-applied automatic door bottom or a surface sweep is the practical choice instead.

Yes. The 350A carries a Fire Rated-UL10c performance rating, and the neoprene extrusion is self-extinguishing, which is why it can go on a labeled opening. Confirm the door manufacturer's label allows a mortised bottom prep, since the routing is done to the door.

Eight lengths are offered: 30, 32, 34, 36, 40, 42, 45 and 48 inches. Order the one that suits the actual door width. The unit is mortised into the bottom edge, so it needs to sit inside the door thickness and width rather than overhang, and aluminum door bottoms of this type are cut down on site when an exact width falls between sizes.

No. On all ZERO automatic door bottoms the spring mechanism activates the seal from the hinge side first, so the insert doesn't scrub along the floor or threshold while the door is closing. That's what keeps the door from hanging up or closing slow, and it's why these last in high traffic where a fixed sweep wears out.

It's rated for 5 million cycles, in a regular duty configuration. That covers ordinary commercial traffic, offices, corridors, multi-family entries. For an opening taking abuse well beyond that, a heavy duty automatic door bottom is the better spec.

The insert is a solid neoprene extrusion meeting MIL R6855 Type II Class 40, which is the oil resistant spec, and it's self-extinguishing. The housing itself is aluminum. That combination suits kitchens, mechanical rooms and loading areas where a foam or vinyl insert would break down.

No, #350 End Caps are supplied with the unit. All you're specifying is the length and confirming the door is prepped for the mortise.

Yes. The plunger is adjustable, which is how you set how far the seal drops for the gap you actually have at that opening. Set it so the neoprene just compresses on the floor or saddle with the door latched, not so hard that it fights the closer.

Clear anodized aluminum. It's a low-visibility finish sitting in the bottom edge of the door, so it reads neutral against aluminum, hollow metal and wood doors alike, and it's consistent enough to standardize across a building's openings.

It's a commercial-duty unit. Nothing stops it going in a residential door, but the mortised prep, the 5 million cycle rating and the UL10c fire rating are aimed at commercial and institutional openings. For a plain interior residential door, a surface sweep is far less work.