On my bench right now I have bobbins loaded with UTC G.S.P 100 AND 75. I really wish I could get 50 in more colors or at least a good tan/brown and a yellowish and olive or light olive would be nice. I like it but it took a learning curve for sure. Started using it on anything with deer/elk hair because it allowed me to pull as tight as I need to get the flare I'm looking for on each particular fly. Also doesn't seem to get brittle if you take a few years to use a spool. If you use an undercoat of white thread you can get a nice color dry or nymph body that won't change colors when wet. One of the A.K. Best theories I like is that dries in nature don't have a fuzzy body like a dubbed fly. Biots or quills make a nice semi shiny body but quills crack at the worst times. by laying down a thread base of white or other colors then layer a GSP body over the top I can get very realistic waxy/shiny bodies like some naturals and with a coat of head cement over them they hold up way past the time it takes me to lose them.