If you aren’t sure of your ring size, and you’re not able to get sized at a jewelry store, this is a great way to do it at home!Simply slide the end through the “buckle” like a belt to make a ring shape and tighten it to a comfortable level, ensuring you’re still able to slip it over your knuckle! The arrow on the sizer will point to the size you are - it’s as simple as that!  Sizes both US whole & half sizes( If you just need to convert your size from another country’s, there are tables online for that.) Please be aware that narrow rings always feel looser than wider ones. For extra wide rings, you may need to order a half size larger. This is very individual however. The sizer is about 4 mm wide.