Stainless 4.2mm stainless steel tubing bent in the same graceful curves as our original model. The mounting spine is a stamped piece of art. This is not a standard metal cage. The finished cage is polished to a brilliant shine and will add to the aesthetics of any machine. Stainless cages are a popular choice for steel frames, randonneurs and gravel bikes. It is also well-proven at the top levels of competitive cycling. It&';s adorned the winner&';s bike at Paris Roubaix and carried bottles securely in Flanders, the Tour de France, etc.