This is a big bottle of Isopropyl alcohol, useful for cleaning the heads of tape-players (remember them?), camera lenses, the platons of photocopiers and scanners, electrical contacts and virtually anything else that doesn't take kindly to water, is immune to the charms of WD-40 (which in any case leaves its own residue) and needs a good degunking. Isopropanol is ubiquitous in its many uses, and occupies the mid-point between soapy water and acetone when it comes to getting stuff really clean.
This is a _big_ bottle. If you have a lot of degunking to do, this would be the one to go for. If you're merely interested in rescuing some ailing components or glassware, then a much smaller bottle would suffice.
Beyond that, there really isn't much to say. Some people prefer to use whisky: this is better, and it doesn't waste the whisky.