This unassuming blue box is without doubt the most consistently popular niche guitar effect, and its presence on a 'board is a pretty reliable indicator that a player has spent some time poring over online forums.

At its core it's a delay pedal, but expands its sonic horizons by rethinking how to use the digital buffer - the 'copy' of your signal that is delayed - to make the effect. Examples of extra control on offer are how fast a buffer is played back, and which direction it is played.

With some additional setup, intervals can also be quantized, and it has an expression input that can be used to control pedal parameters.

If that weren't enough, there's two other modes - a looper that allows playback of a loop in slices, and a second loop mode that allows a clip to be played back with three virtual tape heads over which there are various controllable parameters.