Rothco Pith Helmets Olive Drab. Rothcos Pith Helmet is made of high-density polyethylene that is waterproof. The helmet is one size fits most with an adjustable hook and loop strap on the inside on the helmet. made in specialized factories. Specifications for Rothco Pith Helmets: Manufacturer: Rothco Gender: Unisex Age Group: Adults Hat Size US: One Size Fabric/Material: 100percent Polyethelyne Size: One Size Package Contents: Rothco Pith Helmets Rothco 5670-OD: Pith Helmets Olive Drab