Note: Ensure you select correct orientation for your extruder and compatible, reverse for HextrudORT extruder and Creality DDX for default. Compatible table: https://support.dremc.com.au/support/solutions/articles/51000344580-idga-ridga-compatibility-table Be aware the primary drive gear is reversed :not compatible with the Bondtech BMG extruder Reverse: This Assembly replaces the following drive train items: Main shaft; Main gear; Set screw; Primary drive gear. Be aware the primary drive gear is reversed :not compatible with the Bondtech BMG extruder We recommend using 4x8x3.0 mm ball bearings (NOT INCLUDED). Compatible with : new design of the HextrudORT See below for more information for support for Sherpa https://github.com/Annex-Engineering/Annex-Engineering_User_Mods/tree/main/Extruders/Sherpa_Micro/Extruder_Mods/Churls_Micro_RIDGA Or Direct Swap: https://store.dremc.com.au/products/oem-ridga-v2 Default: This Assembly replaces the following BMG drive train items: Main shaft; Main gear; Set screw; Primary drive gear. Be aware the shaft is 28.1mm long : not compatible with the Bondtech BMG extruder We recommend using 4x8x3.0 mm ball bearings (INCLUDED). Bondtech DDX for Creality extruder Bondtech BMG-HT for FunMat HT Be aware the shaft is 28.1mm longnot compatible with the Bondtech BMG extruder Technical Specification Shaft length: 27 -0/+0.05 Shaft length to support ball bearings : < 3mm – 3mm > Filament teeth’s center to end of shaft : < 14mm – 13mm > Number of drive gear teeth : 17 Drive gear teeth length : 4mm Mainshaft/drive gear Material: Hardened SteelMaterials Compatibility: Flexible : yes; Rigid : yes; Abrasive : yes. Number of main gear teeth : 50 Main gear teeth length : 3mm