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 » Connectors » 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 WIFI OBD2 Adapter 50W LED with Color Temperature of 6000-6500 K JGB37-3530 DC Gearmotor (333 RPM at 12 V) TDA7492P Audio Amplifier Module with Bluetooth Receiver 5pcs USB LED Lamp