Slipknot have announced details of their upcoming one-day festival, Knotfest Iowa 2021.Set to take place at the National Balloon Classic Field in Indianola, IA on September 25, the long-running metal band will headline on the day.The likes of Faith No More, Megadeth and Lamb Of God will also perform at Knotfest Iowa 2021, while $uicide Boy$, Gojira, Trivium, Tech N9ne, Knocked Loose, Turnstile, Gatecreeper and Vended are all set to play.You can see the line-up poster for Slipknot’s Knotfest Iowa