The new HF9 Flat Iron gas hobs from Hoover reinterpret a classic has hob. The new hobs offer bold innovative design, featuring smooth satin finished surface, maximum efficiency hi-tech burners and reduced vertical depth. When you turn the control knobs on, a soft blue light stays on to remind that the hob is cooking and gas is flowing. The Flat Iron hob comes in 75×52 cm 4-burner or 90×40 cm 3-burner configurations. Hoover. Previously, 5-burner hob.