Each set of Signature rings comes with two sets of inserts. Each insert is marked "0" (zero) meaning it is a concentric insert with no offset.

You can also purchase a set of inserts which come with three differently sized offset ring inserts, one +.050", one +.010", and one +.020". For a full description, you can look on the Burris web site, or on the Midway USA web site (MidwayUSA part number is 712472). They can be purchased at most of the usual places.