FITTR HART Sizing Kit (Confirm Size Before You Buy HART Smart Ring)
The FITTR HART Sizing Kit is a pre-purchase sizing set designed specifically for the Fittr HART smart ring, using sample pieces in sizes 6 through 13 to help you choose a comfortable fit. It is meant to reduce the risk of ordering the wrong ring size, but it is not a universal sizer and the kit itself is bulky compared with typical ring gauges.