Traditionally, a double end bag is a small punching bag that may have an attachment from two ends, that is the ceiling and the floor. The two ends are fastened with straps. However, there are bags that are tied only from the ceiling. That way, when you punch it, it'll swing freely and in an unpredictable way. The double end bag functions on its own whims, as it can get back to you without you having the slightest inkling.