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 » All Products » 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 JGB37-520 DC Gearmotor (7 RPM at 24 V) SX1278 LoRa Transceiver (433 MHz, 3000 m) M328 Multi Component LCR Tester with Graphical Interface CC2541 iBeacon Module JGB37-550 DC Gearmotor – High Power (175 RPM at 12 V)