Built from a kit amp from the Hesslerk Etsy store, so expect the same electronics and performance from this very popular and sought after design. Newly built a couple of days ago and unused but tested to ensure functioning. Runs on a 9V battery (supplied) which is replaced by lifting the hinged lid. Unlike finished units sold by Hesslerk. which have a small restrictive hole drilled in the bottom to allow speaker sound to emit, this unit is operated by opening the top lid to allow the speaker to "breathe" and freely emit it's sound - see second pic. Groovy and "sweet" (as candy), this cute handy pocket unit will give you "sounds-on- the-go". This repurposed altoids tin makes a smart and funky gift for friends or family.. Use with your smartphone, mp3 player, or ipod, etc, by connecting your cable (not supplied) to the 1/8" jack socket on the unit. Stereo mixed output that is amplified and delivered to the built-in speaker with 10x gain (unlike standard models). Surprising battery life to boot so you won't be left high and dry. Has a dual purpose control for power (on/off) and volume. Just plug in - turn up - and jam to those tunes - anytime .... anywhere