Kangaroo Strop 3x8". Glass mounted strop. Kangaroo is an ULTRAFINE surface. Smoother than a baby's butt. It takes compounds extremely well and is EXTREMELY thin, minimizing inadvertent edge convexing. It's also an extremely strong leather. In particular, I find that 'roo works exceptionally well with grits 0.125 micron and below because it doesn't provide much if any abrasion on it's own, letting the compounds 'shine through'. It should work well enough on some of the coarser compounds, but I find balsa more than adequate for those too. It also has a nice consistent draw.
The 3x8" strop is mounted on glass blanks. I'm extremely pleased with how these came out. I've selected extra thin Kangaroo leather specifically because it is so thin that the amount of 'give' is minimized. Smooth? You bet! Some of the smoothest leather I have ever felt. I'm considering it an ultimate strop, especially well suited for ultrafine compounds below one micron going all the way down to my finest compounds (0.025 microns - ten times finer than quarter micron). In the extreme, it can also be used without compound and has the 'draw' associated with leather. Pictures can't truly capture the smoothness, which must be touched to truly believe just how fine it is.