You need a gas hose to connect your stove or hob. You connect it to your gas supply, so that you provide your cooker or hob with gas. Please note that a stainless steel gas hose is required to connect a cooker or built-in hob. Do you have a free-standing hob? Then you can use a rubber gas hose. This dries out slowly and must be replaced every 5 years. With a connection set you can buy all the supplies in one go.