Add some extra height to your sofa, chair or ottoman with these attractive and sturdy legs, The hanger bolt is an 18 thread count, 5/16 of an inch; diameter. If your measurement of the hanger bolt diameter is around 1/4 of an inch; then it is a 5/16 of an inch;. But if it measures closer to 3/8 of an inch then it is 10mm. The most common size hanger bolt for most furniture is 5/16 of an inch;. For some imported furniture, the larger Metric 10mm (M10) size is common. These sofa legs will not work with M10 attachment points. These also work great with ottomans, love seats and chairs.