Original Campagnolo replacement cassette lockrings. 
There are four types:

9/10 speed compatible (all 9/10 speed cassettes from 2000 onwards plus Record and Chorus cassettes from 1999)
11 speed compatible (all 11 speed cassettes from 2009 onwards)
12 speed compatible (all 12 speed cassettes from 2019 onwards)
13 speed compatible (all 13 speed cassettes from 2020 onwards)

Please also check what tooth your first sprocket is:

Select 11T - for 11 tooth first sprocket
Select 12T - for 12 or 13 tooth first sprocket

FEATURES:

Original Campagnolo Spare part

CAMPAGNOLO PART NUMBER

CS-501 (9/10x, 11T)
CS-401 (CPS45 9/10x, 12T)
CS-111 ( 11x, 11T)
CS-112 (11x, 12T)
CS-511 (12x)
AC21-N3W (13x 11T)