Steel ball cup, 10 mm ball, 21 mm centre, M8 × 1.25 thread, external clip

Metal ball cup for a 10 mm ball, 21 mm centre distance and M8 × 1.25. thread with an outer retaining clip.

It is the articulated end fitting of the gas spring: it clips onto a ball stud of the same diameter and lets the assembly pivot as the lid or tailgate opens.

Two dimensions have to match. The 10 mm ball diameter must be the same as the stud it mounts on, or the cup will not clip on. The M8 × 1.25. thread goes onto the gas spring rod and belongs to the 10/22 series. The 21 mm centre distance sets how far the pivot sits from the rod end.

Ball: 10 mm · Centre: 21 mm · Thread: M8 × 1.25.