The PRO Axle Alignment Guide from Pinewood Pro helps you insert your axle into the pre-cut pinewood derby axle slot.Pinewood Pro's exclusive patent pending design is a one piece axle guide that slips into the pre-cut slot on your block.No need for extra tools or adjustments.Just hold the Guide on your derby block by pressing your thumb into the small depression, inert your axle into the slot, then turn the block on its side and press the down to slide the axle in.The PRO Axle Alignment Guide includes a wheel spacer to you give you perfect spacing so your wheels don't bind or wobble.Perfect spacing and straight insertion = a faster car!