You're right. It's a S100s. But I never said anything about it being 'run of the mill', unless that was edmorel's attempt at a pun. I think the original GB -- this is going way back now -- was S100s. More recently, it can be any yarn number and is often a mixture of more than one, which is why they don't stick a number on it. Also, GB is differentiated at pretty much every stage of the process, not just in terms of micron, but everything -- length, crimp, spinning, dying, weaving, finishing, etc.