Will it fit? The compatibility guide

1. Cut-out diameter

The round hole in the mailbox door that the lock body passes through. Singapore HDB and condominium letterboxes are highly standardised here, which is why all nine of our models fit the overwhelming majority of mailboxes without modification.

If your cut-out is non-standard — usually a custom landed installation or an imported box — we will tell you from the photo rather than discovering it on site.

2. Door thickness

The lock body clamps the door between its face and the retaining nut behind. Every lock has a usable thickness range, and a door outside that range either will not accept the nut or will never reach proper torque — the slow failure where a lock feels fine for a month and then spins.

Standard letterbox doors in Singapore are thin sheet metal and fall comfortably inside every model's range. Reinforced or double-skinned doors occasionally do not.

3. Cam swivel direction — the one that catches people out

Behind the door, a small arm called the cam rotates to engage the strike. It has to rotate the right way for your particular mailbox, and different bank generations differ.

This is the single most common reason a DIY-fitted letterbox lock fails. The lock is the correct size, it goes into the hole, the key turns — and the door still pulls open, because the cam is sweeping away from the strike instead of into it.

How to take the photo we need

One straight-on shot of the mailbox front, showing the whole door including its edges and the existing lock or keyhole. Straight-on matters — an angled shot distorts the cut-out and we cannot judge proportions from it.

If you can, put a coin flat against the door next to the lock. It gives us a reliable scale reference and turns an estimate into a confirmation.

If the mailbox is currently locked and you have no key, photograph the front anyway. We can identify almost everything we need from the escutcheon and the door.

If we get it wrong, you pay nothing

If we have confirmed a model from your photo and it does not fit when we arrive, there is no charge at all — no attendance fee, no call-out, nothing. The risk of reading your photo correctly is ours, not yours.