Well I’m sure it’s not felt but it’s got that general feel to it... I’m talking about the OEM style ones that crush, seem to be a felt like material in an Aluminum casing.
I’m about to fit a pipe and have both styles on hand, never used Copper ring type, intrigued to know if there is any benefit to either type.
My gut says the OEM style will seal better but the pipe came with copper (I suspect they may be cheaper to produce...)

I’m about to fit a pipe and have both styles on hand, never used Copper ring type, intrigued to know if there is any benefit to either type.
My gut says the OEM style will seal better but the pipe came with copper (I suspect they may be cheaper to produce...)