57mm quad upper and 57mm triple with a becket on the bottom. I think the little block is a 40mm.

Came with the boat, I'm still not totally happy with the way it works, but it's better than it was. The sheet needs to be smaller I think as well, its 7/16 and doesn't run through the blocks very fast. I had 5/16 on my last H16 and if you dropped the sheet it just went ZIIIIIIIING. and you got t-bagged.