Yes4All Adjustable Aerobic Step Platform, 40 in x 16 in with 4 Risers, Black and Grey - Walmart.com
Amazon.com: The Step (Made in the USA) Original Health Club Aerobic Step Risers in Black for Use with The Step Aerobic Platform – Health Club Size (2 count)
Aerobic Step Board Home 28“ Fitness Exercise Health Trainer Workout W/ Riser 718910480361 | eBay