This is a 7-inch air duct specially designed for the dual 120mm fans of the Antminer. It also works with Antminer L7, S19 Pro, eBit 10.2, Avalon 1246, etc. Made in the USA, from high-quality materials that can soften in temperatures up to 190F, they will automatically cut if the temperature exceeds 110F. It's printed in PLA, so there's no risk of fumes, like with ABS and heat. It is printed in black to help reduce noise and allow you to move heat away from the miner.