Spring mattresses are of two types – Bonnel and pocket springs. Bonnel spring is the oldest spring type technology and is currently widely used in the entry level spring mattresses. Bonnell springs are hourglass-shaped. They work together and move as a single massive piece. On the contrary, a pocket spring mattress is made from individual pocket springs. Each pocket spring is enclosed within its own fabric pocket. Working independently from each other, each spring reacts only to the pressure applied to that area.