When a customer refers to a "gauge" they are referring to the Brown and Sharpe (BS) gauge of steel.
The following BS gauge correlates to USP size.
BS 18 = USP 7
BS 19 = USP 6
BS 20 = USP 5
BS 22 = USP 4
BS 23 = USP 3
BS 24 = USP 2
BS 25 = USP 1
BS 26 = USP 0
BS 28 = USP 2-0
BS 30 = USP 3-0
BS 32 & 34 = USP 4-0
BS 35 = USP 5-0

Stainless steel sutures are compatible with MRI/NMR procedures having static magnetic fields of 3.0 Tesla or less - however, there may be some slight image distortion.

Stainless Steel