Longtime Colorado band Big Head Todd and the Monsters will play a pair of concerts at Red Rocks Amphitheatre on Sept. 22, just a day after Colorado singer-songwriter Nathaniel Rateliff ends his Sept. 15-21 run there. The 5:30 and 8:30 p.m. sets, announced Friday by promoter AEG Presents Rocky Mountains, will be all-ages admission and follow the public health orders set for previous, public concerts at Red Rocks this year. That means will be limited to 175 socially distanced, masked people, almost ensuring a quick sell-out. Tickets for the concerts are on sale at 10 a.m.