E. Emerson Tool Co. C50 50-Inch All-In-One Contractor Straight Edge Clamping Tool Guide STRAIGHT EDGE - E. Emersons Contractor Series self-clamping straight edge patented design has integral tubes running the length of the wide body construction, making it ultra rigid and light to handle. NO C-CLAMPING - No more C-clamping! Achieve that truly straight cut using this self-clamping straight edge to guide your tools. EXTRA WIDE - This self clamping straight edge is extra wide for exceptional rigidity and has a low profile for obstruction free cuts. FLAT TOP - The extra low profile and flat top makes it easier for all circular saw or router straight cuts. CONTRACTOR SERIES - Please note: recessed tracks accept Contractor Series Saw Plate, Router Plate, and Stop Block. But it will not work with A, Twin, or Ultra Series accessories.