Throttle butterfly valve and method of producing

A closure element (1) for a gas supply channel, comprises a channel section (2) that contains a throttling flap (3). The flap is moved by a shaft (4), and the channel and flap form a common unit, made of plastic. The flap and the shaft are injection molded, and the flap shaft is held in a bearing (20) and has a lever (6). The element is produced by injection molding the channel section, forming a hollow section for the flap, and then forming the flap and shaft in a second injection step. Bearing members are located in the mold unit before moulding takes place.