Now discontinued and accordingly expensive, the POG was originally the affordable, non-rack polyphonic octave pedal.
Pitch-shifting units like the Whammy had been around for some time, although their sometimes erratic tracking and alien warble wasn’t suited for all players. Moreover, they weren’t polyphonic, meaning that you couldn’t play chords without getting a mashed, bitcrushed version out the other side.
Meanwhile, in the octaver camp, there had been analogue octavers, like the MXR Blue Box, around for decades, though digital units had the same issue as the Whammy - an artificial-sounding tone, monophonic-only operation, and often lacklustre tracking. Moreover, having more than one active harmony, was limited to rack gear.
The POG blew all of this out of the water when it was introduced in 2005, offering highly granular control over several octave modes, a less ‘artificial’ sounding pitch shift, and a wealth of tone-shaping options centred around an excellent core tone.
Known users included Joe Satriani and Nick Zinner of Yeah Yeah Yeahs, and probably the only thing that stopped it being a runaway success, as opposed to the cult success it became, was its large form-factor, taking up the same slab-size enclosure of many old-school EHX pedals like the Memory Man
Even today, the original pedal stands up, though there are plenty of options should you want an updated model. EHX themselves redesigned the pedal in the form of the POG2, while the compact Micro and Nano versions were arguably the runaway successes that the POG line had been driving towards.