FAST-TAC™ TDU™ PANT DETAILS 5.11's® latest innovation comes to one of our most heavily used pants, the TDU™. Fast-Tac™ use a lightweight (4.7 oz.) polyester ripstop fabric with water resistance for the ultimate in lightweight, tactical functionality.  Built from 4.7 oz. Fast-Tac™ Polyester Ripst..