Here's what Blackstar says about the Fly 3 Mini Acoustic Amp:

Whether your acoustic guitar is a parlour, dreadnought, or grand auditorium the FLY 3 Acoustic will give you more. Whether filling out your sound, or angled back to act as a personal monitor, it will instantly enhance the natural sound of your instrument. Every acoustic instrument player should have one in their kit bag.

Features

• Fills out your sound and enhances the playing experience: you don’t know it’s on till it’s off.
• Natural response for all acoustic instruments.
• Linear response speaker is perfect for MP3 playback.
• Expandable to a 6 Watt stereo set-up with the optional FLY Acoustic 103 cab.
• Perfect for music playback or as a PC monitor speaker.
• Up to 55 hours of battery life under normal playing conditions.
• Designed for ukuleles, mandolins and more.
• Built-in echo effect.

Specifications

• Power: 3W
• Shape: ‘Out’ position: a flat EQ response. ‘In’ position: a mid cut with a low and high boost
• EQ: Bass, Treble
• Effects: Echo
• Speaker Emulated Output: Yes
• MP3/Line In: Yes
• Batteries: 6x AA
• Speaker: 3"