Hunt Boston Electric Pencil Sharpener Model 18 and 19 replacement plastic helical gear 70 teeth. Also fit X-acto 18xx and 19xx series sharpeners This fine Nylon gear has improved design 6mm wide face for better durability and performance Our gear is 20% thicker compare to OEM and other replacements It fit snugly and won't slip of the shaft thanks to fine tuned center hole configuration and 15 degree Helical teeth angle Made out of Nylon - tough and flexible plastic Nylon naturally slippery, no lubrication on gear teeth required! We recommend 1 drop of machine oil on to the cutter shaft though. Only Nylons should be used for gears where a slippery surface is desired. All other materials (PLA, ABS, PET, etc.) will grind creating a plastic dust and eventually fail! For details, please review all pictures, or you can find installation videos on YouTube We subsidize shipping cost Material Nylon 70 tooth Diameter 53.8mm Hub width 8.2mm Do not waste your money on ABS or PLA plastic gear that may strip or even melt! If your Boston 19 sharpener has inner gear stripped (incorporated in to ABS plastic frame) Please visit our other listing for a model 19 inner gear guide Sharpener is not included - image is for reference only Thanks for reading.