These are Oak sanding blocks we make and use in our shop everyday.  You add the grit sand paper you want to the blocks. One you can glue the sand paper tothe block,  the other you use a small screw that come with the block to change sand paper as needed. At this time we are selling as a set for 30.00 plus shipping. let us know if you would like sinlge blocks and we can set that up as well.