This publication is not simply an additional book on cross flow turbines. It represents the feasible reply to the need of a satisfactory turbine which can be manufactured without the use of a foundry: the T12 turbine, which is a tested cross flow turbine model. The content of the hard-box is Volume 3 in the MHPG series “Harnessing Water Power on a Small Scale”: Cross Flow Turbine Design and Equipment Engineering and consists of a complete set of workshop drawings, including all detailed drawings and partlists. The box also contains all information required for size selection within the specific application range.