Features: Silicone insulating sleeve is more durable and has better effect. The silicone insulating sock can make the heater block heating faster, it can prevent the temperature spillover of the hot end, and help to keep the hotend temperature extremely stable. After using this silicone sock, you can start the cooling fan at full speed, and print high temperature materials, improve the success rate of printing. Made of high quality silica gel material, which is very durable, can be tightly wrapped with heating blocks, and is easy to disassemble and install. Comes with 3pcs silicone cover. Specifications: Color: Blue/Black(optional) Material: Silicone Quantity: 3pcs Item Size: 23 * 23 * 14.5mm / 0.9 * 0.9 * 0.6in Package List: 3 * MK9 Silicone Sock