Our sets of six rings include one in each standard Spectrum color. These durable flat plastic rings are perfect for building foot speed and agility, but can also be used as giant toss rings, bean bag targets, agility rings or in hoop activities. 36" diameter. The larger diameter, the heavier the hoop will be and usually the easier it will be to keep moving. The heavier the hoop, the more calories are burned while hula hooping.