The quality of the product and instruction you receive is great.

However, there should be better pre-purchase instruction on ring sizing.

The only ring I generally wear is a size 10 (US) wedding ring. Since the 21mm version is approximately size 11.5 (US) I believed this was large enough. It is not.

You need a ring slightly larger than your index and/or middle finger, whichever is larger.

In hindsight, I probably should have realized this and taken the time to get a measurement on those fingers rather than going off the size of my wedding ring but I could see that being a commonly made mistake.

This is a fooler