GATES-LL-2GT Synchronous Belt GT2 Width 6MM Open 3D Printer - GATES-LL-2GT Synchronous Belt GT2 Width 6MM Open Timing Belt wear Resistant for DIY Reprap 3D Printer Parts - (Size: 2M-6MM-2GT). Brand: 3d printer.Gates 2GT Belts - FilastruderMade out of a fiberglass reinforced rubber which means it's chemically resistant, harder wearing and doesn't stretch whilst under stress; Imbued with of nylon 
PowerGrip® GT®2 Twin Power® Timing Belts - GatesPowerGrip® GT®2 Twin Power® Belts feature dual-sided teeth to provide equal load carrying capacity on either belt surface, enabling synchronization from both