34mm Rings that fit 11mm rail

s-l500.jpg

Or you can convert from 21 - 11mm. Have a lot of them, and allow you to switch scope w/mount from rifle to rifle and between picatinny/weaver/dovetail. Very useful.
https://www.ebay.com/itm/Pair-3-8-11mm-to-7-8-20-21mm-Dovetail-Weaver-Picatinny-Adapter-Rail-Adapter/371671970899?hash=item5689603453:g:UWMAAOSwr7ZW6RCC