This 5/16 inch Ruf Rod is one of the most popular sizes because of its versatility in both small and medium size ducts. It is the smallest of the wheel frames, at well under 3 ft. in height or length. Although DCD only recommends lengths up to 600 ft, the standard cage will hold up to 1000 ft. The longer lengths should only be used in smaller ducts (up to 2-1/2” dia) and when there are few bends. The smallest we offer in 5/16: is 200’