These balance discs are taller than other balance disks for a more challenging workout. Recommended for use in proprioceptive strength exercises from the landmark book ProBodx by Marv Marinovich & Edythe Heus. Now adopted by thousands of elite sports trainers in basketball, football, baseball, track, and MMA. Marv is the Professor X of Sports Training, using these discs in his private gym. And Edythe uses the tall balance discs in her studios called Revinmo aka Revolution In Motion. Get a set and see what balance strength training is all about. Poles sold separately.