0.177" (4.5mm) x 24" x 24" Gray Lexan™ 9034 Polycarbonate Sheet | U.S. Plastic Corp.
Amazon.com: Polycarbonate Sheet - 12" x 24" - 4.5mm thickness - Good Glass Alternative used in POP Signs/Displays, Skylights, Pool Enclosures, Machine Guards - UV Stabilized, Low Flammability & Burglary-Resistant : Industrial
Polycarbonate UV2 Clear Sheet 4.5mm Thick 2440x1220mm | Des Munday & Son