Cooking appliance having an external control panel equipped with one or more regulating valves, where the rotary regulator organ is equipped with various peripheral openings for supplying a flow Q. For the supply of one or another type of gas, NG or LPG, either the control knob or a bezel disk in the external panel are interchangeable on the appliance, being chosen between two different available units, one and the other permitting two different angular position limits A2, A3 of the regulator organ or the supply of a constant flow Qmin through one or another opening with calibrated sections, respectively for NG or LP gas. An appendix in the control knob guided in a slide groove on the control panel of the appliance, or a tongue on the bezel disk stopping the rotation of the control knob, determines the travel limit A2 for the supply of Qmin of NG.