Convection microwaves are more expensive than conventional microwave ovens. Gas jets are commonly found in gas stoves, ovens, or barbecues. Heating can be done through the means of ovens, microwaves or steam heating. Halogen lamps are the heating-elements in halogen ovens and ceramic cooktops. None of the restaurants have freezers, microwave ovens, or can openers. Later, magnetron tubes were used as components in microwave ovens. Metallised films are used as a susceptor for cooking in microwave ovens. Flat-panel membrane keyboards are most often found on appliances like microwave ovens or photocopiers. Both are also known as convection ovens. Quality dropped but variety increased with the introduction of microwave ovens and freezer food. Wireless networks are susceptible to interference from devices such as microwave ovens. The magnetron is the type of tube used in all microwave ovens. Both of these resonances are at higher frequencies than the operating frequency of microwave ovens. Thermostats are sometimes used to regulate gas ovens. I experienced cooking pizza in Capodimonte's porcelain ovens.