Dormakaba 75185-XX-01 Simplex Series Latch 1⁄2” Floating Face, 2 3/8” Backset - 3 Hour Fire Rated

The 75185 Simplex latch is a 2-3/8 inch backset latch, so the cross bore in the door has to sit 2-3/8 inches from the edge to the center. That is the shallower of the two standard backsets; if your door is prepped at 2-3/4 inches, this latch will not reach and you need the 2-3/4 inch version instead.

Fire rated, yes. The 75185 Simplex latch is rated for openings up to 3 hours, which covers the typical stair enclosure and area separation door as well as shorter 20, 45, and 90 minute ratings.

Just the latch. The 75185 is the latch assembly that goes into the door edge for a Simplex Series mechanical pushbutton lock, not the lock body, chassis, or pushbutton housing. If you are replacing a whole unit you need the lock itself; order the 75185 when the latch is what failed or when the existing one is the wrong backset for the door you are moving it to.

Two things decide it. First the backset, measured from the door edge to the center of the big bore: the 75185 is the 2-3/8 inch part. Second the finish, which should match the trim already on the door (605, 606, 609, 626, or 744). The XX in the model number is the finish code you fill in. Pull the old latch and measure before ordering rather than going by the lock model, since the same Simplex lock is sold prepped for either backset.

Five finishes on the 75185 latch: 605 bright brass, 606 satin brass, 609 antique brass, 626 satin chrome, and 744 dark bronze. Those are the standard BHMA finish numbers, so a 626 latch matches 626 lever trim on the other doors in a building without eyeballing it. Order the latch in the same number as the lock it goes into and the exposed faceplate will match.

It is a commercial part. The 75185 Simplex latch is built for commercial openings and carries a fire rating, which is why it shows up on stairwells, back of house doors, and multi-family common area doors rather than in a house.