The outer diameter (OD) of a wire insert can only be measured in its free state by first measuring the free coil diameter (FCD) and then counting the number of coils from the notch of the tang to the top of the insert determines its length. The free coil diameter and the number of coils per a specific size insert can be found in the manufacturer’s literature, or generally on their website. Note that wire inserts come in five lengths, each a multiple of the diameter (i.e., 1.0, 1.5, 2.0, 2.5 & 3.0 X diameter) — and that length is the installed length of the insert.