Want to buy stacking rings, but not sure what size to order? Then this adjustable finger sizer will help. The multisizer gauge works like a belt, forming a ring. Place the adjuster over the finger, adjust to give a comfortable fit (don't pull too tightly- make sure you can slip it off over your knuckle). Then simply read off the indicated size. This multisizer is marked with British Ring Sizes A-Z.
Be aware that there are no half sizes.
The ring gauge comes with a set of instructions on how to use it.