Millett makes rings for them but some of the generic rings for 3/8" grooves will also work and some will not. I have Millett rings on my BRNO 611 in .22 WMR, cheap generic rings on my 452 trainer in .22LR and CZ rings on my 452 full stock in .17 HMR and all work fine. I love my CZ rimfires, although the bassackward safeties on the bolt guns is a source of some annoyance.