The 131 Pivot Screw is currently standard on all plastic Fox or Renard bassoons. Prior to 1991 it was the only pivot screw used and will be found on all Fox and Renard bassoons and Fox contrabassoons made during that period. These pivots can be identifed by the abrupt change from the tapered tip to the threads.
The 131 pivot cannot be used on instruments that have been fitted with the 131B pivot. The thread size is the same, but the point of the pivot has different geometry, being smaller and having a more acute taper.
The thread size is #6-32. The screws are made of stainless steel.