We’ve finally found some vacuum plugs that fit the Solex carbs 4mm and 5mm vacuum fittings. Use these to seal up your fittings when using a mechanical advance distributor. High quality EPDM rubber. The extra long length allows you to tailor the plug to the fitting. Additionally, if the plug splits after long use, just snip off the lower part, and reinstall for more life. Set includes two 4mm and two 5mm plugs.