still worry about the become dirty and burnt on the surface after using a period of time? But now this socks will solve your this worry totally. These socks will keep your nozzle clean. They ' t just keep the nozzle clean, but also keep heat inside the hotend, and off the printting. Since silicone is non-stick, your printing head will remain clean and it prevents from sticking to the heater block or nozzle. The additional cooling combined with reduced radiation of heat and nozzle to the printing really boost the ability to make great overhangs and bridges, all while keeping the hotend temperature extremely stable. Features -Material: Silicone - still worry about the MK7 become dirty and burnt on the surface after using a period of time? But now this socks will solve your this worry totally. - These socks will keep your nozzle clean. They ' t just keep the nozzle clean, but also keep heat inside the hotend, and off the printting. - Since silicone is non-stick, your printing head will remain clean and it prevents from sticking to the heater block or nozzle. - The additional cooling combined with reduced radiation of heat and nozzle to the printing really boost the ability to make great overhangs and bridges, all while keeping the hotend temperature extremely stable. - Easy to use, products. Package list: 5 x heating block silicone cases