Function - Check arrow straightness, correctly detect the balance straightness of your arrow, nock alignment, vane and feather balance, to ensure shooting accuracy better. Arrow straightness will influence the precision of your shot Premium Material Built to Last: This arrow spinner tester combines sturdy Aluminum Alloy, ABS and Stainless Steel for maximumreliable. High-precision SS Bearings - SS crowned ball bearings provide large surface to support the arrow and achieve allow smooth operation even under high pressure. Lightweight - Pack it up through quick disassembling, and have it assembled in no time, easy to carry and use. Easy to Use - Put the arrow on the Arrow Spinner and slowly rotate the shaft with your hand. Good straight arrows' arrowhead will stay steady. Fit for all kinds of arrows, such as carbon arrows, fiberglass arrows, aluminum arrows