These standing heavy bags have become extremely popular. This newest version by Everlast is easy to roll away when not in use. It can be filled with either water or sand. The unique flex design has a spring like response that gives the bag a life like feel. This bag is great for home or gym use in any kind of fitness or cross training exercise routine. The base can be filled with up to 24 gallons of water for a 200 lb weight. The bag can also be adjusted to three heights ranging from 52" and 70" tall.