If you’re looking for a selling-style description for the part listed as 31K100091 in the FACOM NS.1010F/NS.1010F2 parts diagram (most likely a replacement internal component for that 1/2" pneumatic impact wrench), here’s a concise product description you can use:

- Replacement part 31K100091 — original FACOM factory spare for the NS.1010F / NS.1010F2 1/2" pneumatic impact wrench. Precision-made to the same fit and mounting points as the factory component, it restores correct alignment of the tool’s internal assembly and protects moving parts so the wrench runs smoothly again. Supplied as a single direct-fit unit to make a straightforward repair; fits the NS.1010F and NS.1010F2 models as shown in the parts diagram.