12-364-6 SPI Zero-Set Plus HolderZero Set for Test Indicator Zero Set is specially designed for test indicators with dovetails and functions as a quick and practical work positioning device. Setting up a workpiece before machining, or aligning the center of a round workpiece in relation to the cutting head, takes virtually no time with Zero Set. Attach Zero Set directly to the collet, then zero in the work position by reading the test indicator. The hardened clamping post consists of