The TK Series In-line Paddle Wheel Flow Meters. Completely Corrosion Resistant Engineering with a true-union design. Available in PVC, PP, PVDF and Stainless Steel. Comes standard with Zirconium Ceramic Rotor Pin and Bushings along with a Tefzel® Paddle Wheel. The Tefzel® Paddle Wheel has been re-engineered for a low-drag, fluid dynamic design that allows it to achieve an industry-leading accuracy of 0.5% to go along with its lifetime warranty.