2mm to 4mm Coupling Hub Hello Customers, we would like to inform everyone that we will not be accepting orders until we fix the issue of disappearing shipping cost from your orders. We are still investigating and fixing the settings so that the correct shipping cost will be displayed in every order. Thank you very much for understanding » Other » 2mm to 4mm Coupling Hub This copper coupler can be used for connection of 2mm to 4mm shafts of RC toys, boats and helicopters. SKU: OTH27407972788 Price: 0.99 $ Product in stock SSL Certificate Quantity Updating cart... This copper coupler can be used for connection of 2mm to 4mm shafts of RC toys, boats and helicopters. Specifications Length: 20 mm Material: Brass Related Products 2GT-20 Pulley (5mm) 2pcs 1 V 100 mA Solar Panel Remote E3D v6 3D Printer Head (0.2 mm nozzle, 1.75 mm filament) M2x14 mm Screw + Nut (30pcs pack) Black 9060 Propeller with 6 mm Hole