Are they 3/4 outside diameter?Have the following Carter & Sons handle adapters, ended up with a bunch of extras. All brand new in their original ziplocs, with set screws. $10 each (1/2 price) + shipping. Take 4 or more and I'll cover shipping (USPS Priority mail, US only).
Link
(6) - 5/8"
(4) – 1/2"
(4) – 3/8"