Review (1/5): Be careful
This product was not what I expected and I was very disappointed in it. In the past I have bought the entire replacement head which was so easy to install. This thing is a kits package and is extermely hard to install. I managed to get two of the three installed. I well never buy this product again. The number sh90 is very confusing. You really don't know that you are getting a kit that you have to install. If I was a watchmaker I could probably do it. I am considering just going back to a safety razor.