Originally Posted by T-Mar

Yoshigai Kikai Kinzoku invented the brake safety lever, which was marketed under their Dia (later Dia-Compe) brand. Weinmann wanted to license the design, but instead they came to a mutually beneficial technology exchange agreement, circa 1963. If you look at 1960s Dia product, you will see that they are actually stamped Dia-Weinmann. Both Weinmann and Dia used circles as trademarks, over struck with their brand name and often with red fill. Anodizing the pivot was a simple way to incorporate the recognizable trademark into the product design. It's also why the bearing washers were typically red and red rubber was often used for pad material. It's all about subliminal brand recognition.