STG O-Ring Service Pack — includes replacement O-rings for key fittings in case of wear or damage. 

Pack contains:

1 × 9×2.5mm
3 × 10.82×1.78mm
5 × 9.5×1.78mm
 2 × 2.6×1.8mm
1 x 11.7x2.65 (STGPROMKII)
1 x 14.8x1.8 (STGPROMKII)

Compatible with, STGPRO, STGSS & STGPROMKII.