3D Filament, Flexible, PRIMALLOY 3mm 500g Reel - White. Developed using Mitsubishi Chemical proprietary materials, Verbatims PRIMALLOY Flexible 3D Filament is a high performance, polyester based thermoplastic elastomer which consists of a mixture of crystalline aromatic polyester block (mainly PBT) and an uncrystalline polyether block (mainly poly-tetramethylene-ether-glycol).