Ringside Apex Boxing Training Platform Speed Bag The Apex Speed Bag merges the traditional benefits of the past with the modern materials and intricate detailing of today This proven training tool will develop speed, timing, strength and endurance when training boxing, MMA, Muay Thai and contact sports alike Punch bag has a sleek tear-drop design that cuts through the air ensuring a fast and balanced rebound with a lightweight latex bladder included Made of durable easy to clean synthetic leather with reinforced triple-stitched seams and sizes measure as follows: XS = 5" x 8", S = 6" x 9", M = 7" x 10" Latex rubber is porous so air will escape w/ each use- Worth the maintenance of light inflation every couple days as they far outperform other bladders- Butyl rubber bladders are heavy & slow and plastic bladders are oblong & have an inconsistent rebound