The Rechargeable Amp Power Pack offers a convenient reusable power solution for select Roland mobile amplifiers that support battery operation, including the CUBE Street EX, AC-33 Acoustic Chorus, and other models. The one-piece design pops easily into the back of the amplifier, eliminating the need to fuss with multiple AA-size batteries. But the benefits don’t stop there?you also get up to twice the runtime over standard batteries, and the amplifier delivers output power and SPL that’s nearly equivalent to using the AC adaptor.*