Review on Enhance Your Kayaking Experience with betobier 4 Pcs Universal Kayak Paddle Drip Rings - Say Goodbye to Slipping and Improve Stability (Black) by Derrick Lowell

I used the supplied o-rings as directed but they were not required for my 31mm blades. The drip rings are very snug on my case with no o-rings. O-rings have an internal diameter of 21mm and are suitable for blades with a diameter of at least 28mm. The o-rings fit into the recesses on the top of the drip rings and fit snugly against the bottom of the drip ring. I have included a copy of the instructions that came with the drip rings. This guide should also be helpful.