Ring Measuring Tool - Made of stainless iron material durable and without rust ensuring long-term application. Knowing ring size was always a problem – with time, one gains or loses weight, so it is always better to have ring measurements for fingers with you. For other first time ring wearers - The Metal Ring Size Finder will only give the ring size for that type of ring. For classic ring fit (flat on the inside), you need to get a set of ring sizers that are completely flat on the inside.