This part is designed to fit into the cylindrical bore wall of fork stems and will work with stems that measure from 12 - 33mm (.5” – 1.29”).

It looks more complicated than it is. Directions are included, but simply match the tapered rubber plug to the hold you're inserting it into. Cut it at the thickest point that will still squeeze through the tube. Then back it with a knurled nut, add a a washer and bolt, and when you crank down the 4mm allen screw it creates a compression plug and locks the RAM mount ball securely in place.