The Spine-O-Meter is a great tester. This is the second time in 2 days I have herd something negitive about it. Depending on what level your looking at the needle at zero, you MAY be off 1# MAYBE. I hardly think that a 1# reading either way will effect anything since we get our shafts in 5# difference. I know for a fact that when we tested aluminium shafts it was spot on every time. Kevin has designed a tester you can test wood, carbon, and aluminium with the same tester. He uses the 26" span for woods and did the convertion for the other 2 types of shafts. Kevin is at the TOP of his class when it comes to this kind of stuff. Sorry for the Rant, sometimes things just rub a person wrong...