A Talon Gearbox Sprocket for Montesa Cota 123 200 240 242 247 304 307 309 310 330 models with the smaller 16mm taper fitting and for a 520 size chain.
Your original sprocket may well have had a keyway, and as far as I am aware, nobody is now making them like this. These Talon sprockets do not have a keyway, but if assembled clean and done up tight, the key is not required, it will not slip.
Available with 9, 10 or 11 teeth, please choose your preferred one from the dropdown. ***Talon have ceased production of the 11 tooth, I have one left, and no more expected***