How many manager challenges does a club get, and how does a manager issue one?

Question

Accepted Answer

Each club gets two manager challenges to start every All-Star Game and postseason game, and one to start every other game. A club keeps its challenge if the replay official overturns any challenged call, and loses it if no calls are overturned. A manager may challenge several reviewable calls within a single play using one challenge. Once a club has used up its challenges, it cannot challenge any further play or call in the game. The manager holds his hands up immediately after the play. The umpire then starts a 15-second timer, and the manager must decide before it reaches zero or the request is denied. The manager must make sure the umpire knows which specific calls he wants reviewed, but need not give his reason. Source: MLB, Manager Challenge (mlb.com/glossary/rules/manager-challenge).