Very close to international ring size standard, measured with digital calipers on inside diameter in mm. I only checked the size 7 and 5.5 because that's all I needed to use from this sizer. Size 7 came out to 17.4mm diameter where my size 7 forged tantalum ring from online measures 17.3mm I side diameter, 6.5mm thickness. International conversion site on Google will show size 7 to be 17.35mm diameter. So I believe the accuracy is pretty good. The sizer rings are also "comfort fit" where the inside is tapered to a point, and the width (thickness) of the sizers is 2.85mm. So if you're going to buy a thicc ring, keep in mind the sizer might seem like its a lot easier to get on and off over the knuckle compared to your thicc ring of the same size.
Accurate and rounded edges (comfort fit tapered on inside diameter)
Reviewed in Canada on October 4, 2019
Very close to international ring size standard, measured with digital calipers on inside diameter in mm. I only checked the size 7 and 5.5 because that's all I needed to use from this sizer. Size 7 came out to 17.4mm diameter where my size 7 forged tantalum ring from online measures 17.3mm I side diameter, 6.5mm thickness. International conversion site on Google will show size 7 to be 17.35mm diameter. So I believe the accuracy is pretty good. The sizer rings are also "comfort fit" where the inside is tapered to a point, and the width (thickness) of the sizers is 2.85mm. So if you're going to buy a thicc ring, keep in mind the sizer might seem like its a lot easier to get on and off over the knuckle compared to your thicc ring of the same size.