There are two basic types of flares used on OEM automotive brake systems throughout the world. The SAE/double (inverted/45degree) flare and the DIN/ISO bubble flare. We will refer to them as SAE or DIN flare. The most common is the SAE flare. Typically found on all American and Asian cars, but the European style DIN flare is appearing everywhere now. Never use a single flare on automotive components. The SAE/double flare standard is remarkably tolerant of production variations, but the assemblies must be the same standard. Single flares are never allowed on steel brake lines.