Thanks to the patient work of research and collection by the authors, the book has been subjected to a consistent work of integration of images and data, offering an almost complete vision of what was the first step towards mass motorization. of the second postwar period. The reproduction of the brochures, posters and original promotional material of each model, provides indisputable technical documentation and to better frame the historical period of diffusion of the micromotors. The book is an indispensable tool for getting to know the many companies that have engaged in this sector, from Bianchi with the Aquilotto to Garelli with the Mosquito, which already enjoyed great fame, to Ducati, which started motorcycle production with the Cucciolo auxiliary engine, up to those with an artisan structure active only for a short period of time. In this way, a general picture of the many technical-aesthetic solutions operated by each manufacturer is obtained, all aimed at making engines with low production and operating costs and easily applicable to bicycle frames.