Which lockcase do I need?

Q: (from Victoria) I am looking order handles for my new doors, S103 mitred lever BSS/PSS and matching bathroom lock set but am unsure which lockcase to purchase.  Could you please let me know which one I need?
A: You can order the “S103 bathroom set, Duel” (which includes the door handles, bathroom indicator set & bathroom lock case), just select 44mm (or 57mm) for the backset dimension - the usual for domestic doors is 44mm, and as they’re new doors you have no pre-cut holes to measure.

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