LED ZEPPELIN Led Zeppelin III (This is something we've never had before because it's as rare as the proverbial hen's teeth, an original 1970 US 10-track white title label promotional MONO LP with no 'SD' prefix to the catalogue number on the label, custom stickered 'DJ Copy Monaural' die cut gatefold picture sleeve with rotating picture wheel & tracklisting sticker on the front. What makes this so unusual is that unlike most mono promos, this isn't simply a left channel blended with the right channel mono but has actually been specifically remastered using the CSG process, exclusively for AM radio stations. This was done because the lead vocals & instruments would often sound too loud when heard played back in mono. When the left and right channels were simply added together, the lead vocals or instruments, being equal in level on both channels, would add up to be 3 decibels louder than the mix in Stereo, so the CSG [Compatible Stereo Generator] process was used to neutralise this effect & create a more natural sounding mono from an original stereo master. This fantastic copy shows just a little edge scuffing to the sleeve & the vinyl is immaculate!).