Performance trends computerized valve spring tester, test everything you need to know about your valve springs in a single stroke of the lever! Spring rate, installed height, coil bind, on seat pressure at given installed height. complete print outs, go back and re test your springs to see if they are truly getting weak. No guesswork you can shim each spring to perfection! Manual tested are a average method of setting up cylinder heads. This unit with software was $1,800 new. I'll sell it and ship it to you for $1,500.00