The ISF allows you to infinitely change the sound of your FLY 3, which gives you endless possibilities on the tone of your amp. The FLY 3 also features tape delay effects, allowing you to make your amp output resonate during play.The FLY 3 also comes with an MP3 / LINE IN jack built in, allowing you to connect to your MP3 player, mobile phone, laptop, tablet etc. and jam along to your favourite tracks; the Emulated Output jack can also be used with headphones. Capable of being battery powered, you can take the FLY 3 with you wherever you go as a set of portable speakers.