Aguilar amPlug3 Tone Hammer, compact headphone amp for bass, Input/Output Jacks: PHONES Jack (3.5 mm stereo mini Phone Jack), AUX Jack (CTIA-compliant 3.5 mm TRRS mini Phone Jack), Power supply: Two AAA Batteries or AAA nickel-metal hydride Batteries, Battery life: 11 hours/17 hours (using alkaline batteries, when FX or RHYTHM is on/off)/4 hours/6 hours (using zinc-carbon batteries, when FX or RHYTHM is on/off), Dimensions (W × D × H): 87 × 33 × 39 mm, with plug folded down Weight: 40 g; not including batteries