For wireless microphones, and really anything that requires serious staying power from batteries, let ProCell be your first choice. Broadcasters, Stage Managers and Theatres all around the world depend on the battery that gives them maximum output for as long (and consistently) as possible. Factory Sound keeps huge volumes of Procell batteries in stock, so you always get great bulk-buy pricing, all year round. PROCELL is made by Duracell - it's their professional user model, high on voltage...low on packaging.