5.11's latest fabric innovation comes to one of 5.11's most heavily used pants, the TDU. Fast-Tac is a lightweight (4.7-oz) polyester ripstop fabric with water resistance for the ultimate in lightweight tactical functionality. The Fast-Tac TDU features a comfort waistband with stretch panels, large cargo pockets for storage and double knees for durability and compatibility with any of our kneepad inserts.