Rear Sprocket 45 teeth for classic CB750K models is typically 48 teeth while 45 teeth acts as a custom/alternative re-gearing option. This vintage sprocket is made of high-grade hardened steel designed to meet OEM specifications for Honda by Okaka Sane Industry Co Ltd in Japan.
As far as we know, this sprocket was never used and was found stored forgotten in a warehouse without packaging for decades. This is a must for those restoring an early CB750K with original parts.