Idle mixture screw control for Solex 26/35 carburettor (24-21 or 26-18), turn clockwise to weaken idle mixture. See description details.

Thread M5x0.5
Total length 31mm
Thread length beneath screw head base 19mm
Total tapered needle length below thread 8mm
Widest part of taper 1.5mm
Smallest end of taper 0.9mm

'May' also fit other Solex, not guaranteed.
32 PBISA16, 12, 
32 PBISA7-11, 12
34 PBISA16,
32 SEI
34/34 Z1
32/34Z2
34 PBISA 5
34 PBISA 3-4-5
32/35 SEIEA
34 BICSA
32 SEIA
35 SEIA
34 PICS
speed