Much easier to set than trying to machine a piece of wood to within a thousandths of an inch. Need longer miter bars available for larger jigs. The price is a bit expensive but the miters can be reused for other jigs or readjusted for years of use.
I used the zeroplay guide bars to make a cross cut sled for my table saw . They worked great and made it very easy to aline the sled for smooth travel on the saw !