[Boxy]

Rajaie has confirmed that his ring is custom sourced from european/US - teflon /US supplier - rubber oring, which went through large numbers of actual fitment and durability tests by US forum members.
I do not know anything about the domestic part beyond a phone call from Mao.
Mao indicates he had the domestic supplier matched these parts from a speciment of the first group buy. Anyone interested in domestic rings should contact Mao for more details.
Regarding coloring, the original bruma ring came with OE Vanos units are black. I believe all Rajaie';s inner rings are of bronish color.
As you are aware colors are used by oring industries to identify product, purpose and application including thermo resistance, chemical resistance etc etc (For instant of air conditioning - R134 and R12 systems are using different colored rings).
To my believe i will be very careful to any part installed in a modern inner combustion engine, especially within a high heat, higher working temperature Bimmer engine which oftenly runs with rubber unfriendly fully synthelic oil. Bear in mind that this us a part to carry high oil pressure which must ensure no leaking at all time.
This is not to deny quality of domestic parts, sometimes domestic suppliers do come up with good product.
Personally I drive a German made BMW, I usually do not desire to use domestic made parts - Call me paranoid, it is totally fine for me - I only use proven parts those offer lower possibility to require replacement in a reasonable time frame - For me the labor cost to replace rings and parts needed to do so are many times costier than the ring itself shall it needs replacement again.