Full metal aluminum dual gear extruder for Ender 3/5 (or even any printer with bowden tube) is FANTASTIC. The M10 PC4 fitting is so much better then the M6 ones in terms
BZ 3D Dual Gear Extruder Dual Drive CR-10S Pro Extruder Upgrade Kit, Works with Ender 3 /Pro CR-10/CR-10S/CR10S Pro, Drive Feed for 3D Printer 1.75mm Filament Industrial & Scientific
No instruction No problem (CHPOWER Dual Gear Extruder, Ender 3 Aluminum Dual Extrusion Upgrade Kit) - YouTube
Review - Redrex Dual-Gear Extruder - 3D PRINTING UK
Cr10 Pro Upgraded Dual Gear Extruder Double Pulleys Direct Aluminum Extruder For Ender 3/5 Cr10s Pro 3d Printer Parts - 3d Printer Parts & Accessories - AliExpress
Aluminum Upgrade Dual Gear Mk8 Extruder For 3d Printer Extruder Ender 3 Cr10 Cr-10s Pro Reprap 1.75mm Drive Feed Double Pulley - 3d Printer Parts & Accessories - AliExpress
Amazon.com: WINSINN Dual Gear Extruder, Ender 3 v2 Upgrade Motor Shaft>20mm, Compatible with Ender 3 Pro CR10 Series 3D Printer TPU Filament Drive Feed (Dual Connector) : Industrial & Scientific