Mila Evolution Gearbox Centre Case 35mm Backset · 92PZ

The mechanism inside your door that the handle and key operate. When a uPVC or composite lock fails, this is almost always the part to replace — no need to change the whole locking strip.

This is a genuine replacement centre case gearbox for the Mila Evolution multipoint door lock. If your handle has gone floppy, the key turns but the door won't lock, or the latch has stopped springing back, the centre case is the usual culprit — and swapping it is a quick, screw-out / screw-in repair.

Built to 35mm backset with 92mm PZ centres and a reversible latch, a single unit suits both left-hand and right-hand doors. Always confirm your backset and PZ against your existing case before ordering — the FAQs below show you how.

How do I measure my backset to check this is right?

The backset is the distance from the edge of the door (the forend faceplate) to the centre of the spindle / keyhole. If yours measures 35mm, this case is correct. We also stock the 45mm version.

What does 92PZ mean and how do I check it?

PZ is the distance between the centre of the spindle hole and the centre of the cylinder (keyhole). 92mm is the most common spacing on uPVC multipoint doors — measure centre-to-centre on your current case to confirm.

Will one case fit both left and right handed doors?

Yes. The latch is reversible, so this single gearbox suits both left-hand and right-hand opening doors.

Is this a genuine Mila part?

Yes — this is a genuine Mila Evolution centre case gearbox, for a correct fit and reliable operation with your existing mechanism.

Is it difficult to fit?

No — most installers complete the swap in around 15–20 minutes (see the three steps above). If your wider locking strip (hooks, rollers, keeps) is also damaged, you may need a full mechanism instead.