One of the reasons I'm such a die hard fan of aluminum arrows are the consistency in spine and weight. I have several dozen, some new, some 20 years old or more and I can pick up any of them and they group together. I don't know how the several dozen that I have differ in tensile strength, they may be all the same for all I know, but I can't say that I'm able to tell a difference in durability. The discontinued Autumn Orange and wood grain classics are hands down the purdiest though.