They are a snug fit on the stock o2 brake bleed screw nipples. They keep these fittings clean; who wants naked nipples? I've been running them for 3,000 miles and they work just fine.
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1976 sahara A 2392532
1974 polaris A 4281992
1971 nevada 2571108(parts only)
2000 MB CLK430
2002 BMW R1150RS - SOLD :^[