A good source for O rings ( and a lot of other good stuff) is
Mcmaster Carr. http://www.mcmaster.com
search O-rings on the site. You should find out everything you want
to know!! As far as duribility is concerned Black is always better–
It will contain a carbon filler that protects best against UV damage.
Mcmaster Carr is an old “Industrial” supplier and will supply quality
materials, Generally US made at reasonable prices.
They sell to everyone, have no minimum order, stock everything, ship
now, take credit cards.
If you live near NYC -Phila. Atlanta, Chicago or LA expect immediate