There may be better testers out there, but I’ve yet to find one.
After extensive research into spine testers where I looked at far more expensive digital arrow spine testers and other such gadgets that you may want, but the one from Heritage will be the only you’ll ever need. Made from very sturdy and strong 5mm thick acrylic with a clear acrylic pointer it has two lines to zero the pointer for higher accuracy when matching arrows. It’s fully adjustable for different diameter shafts and has easy zero adjustment with 2 separate points for calibration. It’s so quick to assemble and full instructions are supplied along with everything needed to put together. As with everything from Heritage it is made for archers by archers and the customer service is outstanding.