Shimano OE replacement Dura-Ace 7800 53t outer ring. B-type is designed fpr best shifting with a 39 tooth inner ring. Due to the perfection of lifting pins and ramp placement from Shimano's engineers, you can expect crisp shifts between rings. Creative machining scallops and hollowed out alloy for weight reduction. Cut not stamped, anodized and polished - there is no doubt this is Dura-Ace quality.