Premium quality synthetic 1000 grit (medium) Japanese Waterstone.
1000 grit stones are used for sharpening prepared tools, they remove wear bevels quickly but leave a refined surface that is ready for polishing. Don't try to do too much material removal with a 1000 grit stone - if you are doing more than a dozen strokes on it, you probably should have started with a coarser stone.
185mm x 63mm x 25mm