The Libero is basically a way to get a defensive specialist into the game without having to use Team substitutions. Teams may designate the following: TWO Liberos for the MATCH or the team may designate ONE Libero for the SET (teams can also choose not to designate any Liberos for the match).  The Libero(s) must wear a different colored uniform than the rest of the team and may play along the backrow only.  There are specific things the Libero can and cannot do (cannot attack the ball while above the height of the net, and others - please see Rule 19 on pages 65-69 of the 2019/2021 USAV Domestic Competition Regulations for full explanation). Libero replacements are not counted as a Team Substitution. Each team may use up to 12 substitutions whether they use a Libero or not.