The zero tolerance upgrade makes the rage 5s useable as it should have been from day one. The part is well made and allows the saw to make accurate, level thin cuts. The saw is now working as it should have been. BUT....I cannot give it 5 stars as it's pretty off to have to pay an extra 10% of the original purchase price just to have a tool that does now what it should have done when bought. I would be more than happy to hear from someone at Evolution and have them attempt to justify that to me. Better still, refund my "upgrade" costs, paid to make a product work as it should!