PRO-GLAS Fiberglass Reinforced Filler, Gallon PRO-GLAS Fiberglass Reinforced Filler combines the durability of fiberglass reinforcement with the workability of light weight filler. Specially formulated and approved for SMC and rigid plastic repairs, smooth and creamy PRO-GLAS mixes easily, spreads smoothly and has excellent sanding for a smooth refinish surface. Short-strand fiber reinforcement delivers unbeatable strength and maximum adhesion for tough repairs while the creamy texture maximizes workability. Fiberglass reinforced and easy to use - PRO-GLAS delivers the one-two punch for a winning finish 25050