Cross-cut safely and accurately on your table saw. A pair of UHMW (Ultra High Molecular Weight) plastic runners are a great solution for your cross-cut box. Wood is not recommended for use as runners for your cross-cut box. Wood will expand and contract with changes in humidity which will either make the fit too tight or too loose causing the sled to either bind or wiggle in the slots.
UHMW plastic will not change dimension with humidity changes and is very durable. I have been using the same pair of runners on my box for over twenty years. The runners ride in the slots on the top of your table saw to guide your box. The plastic makes the fit tight and the sled will glide along nicely as the plastic acts almost like a lubricant against the metal.
Price is for a pair (2) of runners. Trim width for a perfect fit.