Spiral router bits are made by Amana Tool, the leading manufacturers of high quality wood cutting tools. Use Amana Tool 57176 Solid Carbide (Brazed to Steel Shank) Spiral Pattern/Plunge Compression 7/8 D x 1-9/64 CH x 1/2 Inch SHK w/ Upper Ball Bearing Router Bit for trimming laminate work or for template and pattern work. For template application, the bearing follows the template, while the cutting edge trims the workpiece. With the router handheld, the template is on the bottom of the work. With table-mounted router, the template is on top. Diameter (D): 7/8; Cutting Height (B): 1-9/64; Shank (d): 1/2; Overall Length (L): 3-15/16; Replacement Collar: 47739; Replacement Bearing: 47793; Flutes: 2.