The PG02B Fence Extension is Morton's answer to the customers who want the ruler back on the squaring fence. The old PG01 had a ruler and fans of this function want it back. The ruler has inches on one side and metric on the other and is attached to the extension by the user. The PG02B comes with two rulers for options of left or right handed and inch or metric scales. The extension adds 5" to the PG01B Squaring Fence and can be placed on either side. (only fits the New Portable Glass Shop). The ruler is marked in inches on one side and metric units on the other.