Some trike conversion sets can also be used with recumbent bicycles to form recumbent trikes. JZR Trikes is a UK producer of traditionally-styled, motorcycle-engined trikes in kit form. Some trikes have a push bar so adults can control the trike. Fully enclosed bikes and trikes are considered velomobiles. Wheeled toy licensee MV Sports & Leisure Limited produced a range of scooters and trikes. Many manufacturers have designed and released hand-powered recumbent trikes, or handcycles. Manufacturers of recumbent trikes include Greenspeed, WhizWheelz and Inspired Cycle Engineering (ICE). The center of gravity is quite high compared to recumbent trikes. Zanella also produces the ZMax series of three-wheel motorcycles (trikes) and light trucks. Other trikes include ATVs that are specially constructed for off-road use. The smaller motorized trikes are used as delivery vehicles for lighter loads. Delta trikes generally have higher seats and a tighter turning radius than tadpole trikes. In 1991 Grinnall started to produce three-wheelers (also known as Trikes). The company specializes in the design and manufacture of ultralight trikes. Electric trikes have also been produced that conform to the e-bike legislation.