This tube will fit both 597 and 590 ISO or 26x1-3/8 and 26x1-1/4 sizing. 26x1-3/8 (590 ISO) is common for most English 3-speed, department-store or juvenile 10 speed. 26x1-3/8 and 26x1-1/4 (597 ISO) are common in Schwinn "lightweights" or older British sport and club bikes, respectively. If your tire is an "S-6" then it will take a 26x1-3/8( 597 ISO).
**Special return policy for inner tubes** Tubes can only be returned because if a manufacture's defect is at fault – separation a bond at a seam or valve joint. A tube can not be returned due to a puncture, improper installation or tearing at the valve joint.