Both gears are made of Hardened Steel , and plate nickel, which can prevent from rusting so that it can work for long time. The hardened steel extruder gear assembly is an internal component of the hardened steel extruder unit. It comprises a driven gear and an active gear that work together to feed filament into the hotend. Built with heavy-duty materials, the extruder gear assembly is designed for long-lasting performance. However, if abrasion or clogging occurs due to extended use, the extruder gear assembly can be easily replaced. Thanks to its hardened steel gears, the extruder unit is capable of printing with tough engineering filaments like carbon fiber nylon and glass fiber nylon. The P1P stainless steel extruder can be upgraded to a hardened steel extruder by just replacing the extruder gear assembly. The extruder gear are made of stainless steel, if you print tough engineering filaments like carbon fiber nylon and glass fiber nylon, than it get abrasion,so in this case, we suggest you to use this Hardened Steel one. Reduction Ratio:9 : 53 Supported Filament Diameter:1.75 mm Supported Filaments:PET-, PAHT-, PA6-, PLA-, PETG-, PLA, PETG, ABS, ASA, PC, TPU For P1P owner Due to different batches, there may be differences in product appearance, color, and printed text, which not affect the use. type:hardened steel Colour:yellow+silver Material:plastic+metal Package Contents: 1 x Extruder Gear Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.