I have yet to install them but I have no problem reviewing ahead of time, as I know how good Concept Z is. Each type of o ring is separated and organized in their own sealed bag. Came with part numbers on each bag so you could match it up with the website. Everything is in brand new condition. Would recommend for anyone who has an AC leak in their system, or has converted their early model Z's from r12 to r134a. That way the old r12 o rings don't corrode when exposed to r134a. Great product!