Is designed to apply drywall mud and joint tape together on flats, butt seams and inside 90° drywall corners. Automatic Taper features corrosion-resistant, coated, aircraft-grade aluminum which resists job site damage and provides superior durability while prolonging the plunger life and reducing seal leakage. Our urethane cup seal lasts 50% longer than traditional rubber seals used by the competition. The cast aluminum head components are precision-machined from high-grade cast aluminum that will not corrode or break down over time. Stainless steel side and internal plates enhance the performance, increase the durability, and will not corrode over time. All of this up to 3 times faster than hand taping!