ALL the latest Thunder Tiger series engines have been designed to combine the high performance with easy handling and maintenance using modern CAD computer technology. Major components of the engines are machined from the highest quality materials using state-of-the art CNC manufacturing techniques, resulting in consistently high quality and reliability. The PRO series helicopter ring type engines are equipped with dual ball-bearings, Schnuerle porting, one ring type piston/cylinder assembly and two-needles automatic mixture control carburetor.