Could someone help me in understanding the purpose of this silver adapter ring? I have a 2 1/8" borehole, the manual only mentions its removal if you have a 1 1/2". Yet none of the YouTube tutorials I've viewed address this ring.

Additionally, I'm working with the Schlage Century trim plate. It doesn't seem aesthetically pleasing to position it between the deadbolt and the trim board as suggested by the menu, since it would result in a visible silver ring. The only way to achieve the looking from product page is to place it inside, between the door and the trim plate. I'm unclear about its function nor if this is the correct way to install it. Any insights would be greatly appreciated.

Thanks, Chris

enter image description here

  • Can you tell me where you can see the silver ring after installation? Does your lock cover the entire hole in the Century trim, or can you see the adapter ring through the hole in the trim? It seems like your lock cylinder might not be compatible with the Century trim you have, since it requires an adapter for a 2⅛ bore hole.
    – user148424
    Commented Jan 25 at 17:58

2 Answers 2


For this door you'll use the adapter.

The adapter is for use with modern 2-1/8" bores. In decades past, deadbolt bores were smaller--the size of the cast cylinder we see inside the adapter. Schlage used to offer a stamped steel washer to expand the smaller deadbolt body to the larger bore. Now the deadbolt body is large, but accommodates both bore sizes with this adapter.

Modern (deadbolt body and latch plate roughly the same size):

enter image description here

Legacy (deadbolt body smaller than latch plate, adapter ring installed for modern 2-1/8" bores):

enter image description here

You're probably right that the adapter would go behind the Century trim, but I'm not as familiar with that part. It should be fairly obvious, though, whether you can use the adapter with that trim and whether it's needed for centering.


The adapter ring is intended to go inside the door to keep the lock from moving around inside the door if the hole is larger than 2⅛". Since your hole is only 2⅛" you don't need an adapter.enter image description here

  • The adapter in the question photo is to do as you say if the bore is 2-1/8". The one you point out is not what's in the question. It's an additional part, akin to the legacy ring I show in my answer.
    – isherwood
    Commented Jan 24 at 18:09

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