Suitable e.g. for the following carburettor types:
PHBG: AS-AD 15-16-17-17,5-18-19-19,5-20-21 PHBG: BS-BD 15-16-17-17,5-18-19-19,5-20-21 PHBG: CS-DS 15-16-17-17,5-18-19-19,5-20-21