Made from 1/4"" thick phenolic for durability. * Pre-drilled for Porter-Cable 690/890 routers or routers with 6"" base footprints. * Single pivot can be locked to make circles up to 52"" diameter. * Maximum difference between minor and major axes is 8""; maximum length for major axis is 52"". * Includes jig arm, jig base, two dovetail keys, and two locking pivots.