Yes. The XB11-916 kit is ordered by door thickness, and 2.5 inch is one of the choices along with 3.0 and 3.5. Standard B600 Series hardware is built for normal commercial door thickness, so anything over 2 inches needs this longer screw and tailpiece set to reach through and engage.

Three thicknesses are offered: 2.5, 3.0 and 3.5 inches. Measure the finished door at the bore, including any applied cladding or face material, and order the size that matches. The tailpiece and screw lengths are sized per thickness, so ordering the wrong one leaves the cylinder either standing proud or the tailpiece short of the crank.

No. The XB11-916 is a screw and tailpiece conversion kit for B600 Series locks on doors extended equally over 2 inches to 4 inches thick, so it supplies the longer through-bolt screws and tailpiece that span the extra door thickness. The GMS KIT-PART04 is a collars kit for cylinders, which addresses cylinder trim depth rather than the mounting screws and tailpiece of a B600 deadbolt. If the B600 lock is being fitted to a 2-1/2, 3, or 3-1/2 inch door, the XB11-916 is the part that matches the door thickness.

Extended Equally means the added thickness is split evenly between the two faces of the door, so the lock sits centered in the bore and the same amount of extension is taken up on the inside and outside. The XB11-916 kit is built to that EE arrangement. If your door is furred out on one side only, the parts will not center correctly.

No lock parts come with it. The XB11-916 supplies screws and a tailpiece only. You reuse your existing B600 Series deadbolt, cylinder and bolt assembly, and swap in these longer components. If the existing bolt or strike is worn, order those separately.

Not with the XB11-916. Its stated range stops at 4 inches, and the offered sizes top out at 3.5 inch door thickness. Above that you are outside what this conversion kit covers and will need a different special-parts solution from Schlage.

No. A core swap changes the keying, not the mounting length. The GMS IC6-26D is a 6-pin small format IC core only, supplied un-combinated without keys, pins, springs, or caps, and the IC7-26D is the 7-pin equivalent. Neither adds screw or tailpiece length. For a B600 Series lock going into a door extended equally over 2 inches to 4 inches thick, the Schlage XB11-916 screw and tailpiece conversion kit is the part that makes the lock reach through the door.

They do different jobs. The Trimco 1268 is an anchor plate measuring 3-1/2 inches in diameter, used as a backing plate at the door face. The Schlage XB11-916 is a screw and tailpiece conversion kit that lengthens the fastening and drive components of a B600 Series lock so it can be installed on doors extended equally over 2 inches to 4 inches thick, offered for 2-1/2, 3, and 3-1/2 inch doors. A thick-door B600 installation needs the conversion kit; the anchor plate does not change the reach of the lock.

The GMS ICM7-ST is a Best SFIC straight mortise housing in 7-pin with a Yale cam, which is the part used when a mortise lock body needs an IC housing. The Schlage XB11-916 is not interchangeable with it; it is a screw and tailpiece conversion kit for B600 Series locks fitted to doors extended equally over 2 inches to 4 inches thick. Choose the mortise housing for a mortise cylinder prep and the XB11-916 when the issue is door thickness on a B600 lock.