A lockring must match the hub and the smallest sprocket in use.
Campagnolo hubs built as of 1999 until today use 27 mm, Shimano uses 30.5 mm
Campagnolo 9 speed hubs built 1998 and earlier require a 26 mm lockring.
Cassette starting with 11 T require a non standard lock ring that carry an "11" in their name.
Standard lockrings such as GMRSL, GMRCL and GMRCL99 cover all other start sprockets.