Screws, bolts, spacers, and clips are the last-mile hardware that holds the whole machine together — literally. When you're doing a repair and the original hardware is missing, damaged, or stripped, "close enough" from the local hardware store almost never is. Metric vs imperial, grade differences, head styles that won't clear the neighboring part.
This is the genuine Nilfisk Advance OEM NUT M4 NYLON INSERT, part number GT13014, brand new in the box. Right fastener means everything torques correctly, seats correctly, and stays put.
Not sure this is the right hardware for your machine? Send us the model and serial and we'll get you the exact right one.