This third volume in the Rupert Ratio Unit Single Manual, examines those BSA (and Triumph) Unit Singles which were made in low volumes or for special orders for overseas markets, the military and police. It aims to fill many of the small gaps in the Unit Single story by covering the low volume models which are usually overlooked. Not strictly a manual since the procedures for disassembly, repairs, re-assembly and parts identification have been described in detail in Volume 1: The Engine and Volume 2: Everything But The Engine, Volume 3: Lesser Known Models describes why these models were made and the differences between them and the more common Unit Singles. Where available, specialised BSA Parts Lists are reproduced to ensure the restoration enthusiast has as much information as possible to restore these models to the original specification. The book covers the C15 Trials Pastoral, a number of Police Models, Military Prototypes, The C15 trials and scrambles 'Special' models, the B44GP, TR25wC and B44VSC, and the elusive B25 Woodsman only ten of which were ever made. It includes rare original BSA parts lists for these less than common models, and additionally for the more common models, interim dealers parts lists covering the years when no standard parts books were produced by BSA. Volume 3 completes the three volume work The Rupert Ratio Unit Single Manual and will be an invaluable publication to those lucky enough to own one or more of the rare models which have found their way into these pages.