Hello, I'm new to collecting Gillette Old Type Razors. I was wondering if there is a difference in the model 100 vs 102 single or double rings in the way that they shave? Earlier years vs the later years up to say 1921. I have a 1913 year and was wondering if it is similar to say an earlier double ring. For some reason I have become obsessed the these old types and would like to learn as much as I can about them. Thanks