Black in color Semperfli GSP Wax is specially formulated for GSP threads. Semperfli GSP wax is specially for GSP threads so will work with not only Nano silk but Veevus, Uni, Roman Moser and other GSP threads also!
Fly tyers waxed are normally made of a wax (Bees, Petroleum waxes) and a Rosin forgrGip. The melt point is usually around 40 to 50C. Rosin often forms little sharp edges which can actually cut gsp threads. So with GSP wax Semperfli reformulated the wax components in Semperfli GSP wax is without rosin so that it does not rip the fine threads of GSP threads (in the same way a brass bobbin holder can break GSP threads).
Size of the wax piece is about 3 cm x 1,5 cm.