Weiler Vortec Pro Abrasive Flap Discs - Made from zirconium and phenolic backing. Weiler Vortec Pro Abrasive Flap Discs are constructed from zirconium and phenolic backing. These disks are ideal for a working angle of 15 Degree -25 Degree. • Material: Zirconium Phenolic Backing. • Type: Abrasive Flap Disc. • Weight: 0.28 lbs. • Abrasives: Flap Discs. • Features: Ideal for a Working Angle of 15degree-25degree Phenolic Backing. • Sold as 1 Each.