From my own experience the Norton 4K/8K should be required equipment for any straight shaver. Basically you can do it all with just that one stone (well almost all anyway). The yellow coticule is great to put a great finishing edge on the blade but its not necessary but yes its very nice. I have one and use it all the time. Thats not to take anything away from using barber's hones and pasted strops. There are many routes to the destination. you pick the one you want to follow.