Veevus makes many sizes of both GSP and non-GSP. The problem I've had with their 18/0 GSP is that about half way through the spool the filaments are wrapped around each other and I can't untangle them. Veevus is cheaper and you get more per spool than the Semperfli GSP, but it's not cheaper if you can only use part of the spool. I've never had that problem with Semperfli 18/0. Plus, Semperfli comes in many colors in its 18/0 and Veevus only makes it in black or white, as PT said, if that makes any difference.

Joe