Studio aerobic step supplied with 4 feet enabling adjustment to 11 16 or 21cm feet and base have non slip pads extra feet available separately no assembly required this product is easy to use and to change to suit the performer using it these are great for power training you can use the studio aerobic step inc 4 feet to do lots of different exercises you can also use them with other product for example if you use the studio aerobic step inc 4 feet under our york olympic fixed flat be