I don't usually write reviews but this time I felt I had to. Throw away those little black rubber blocks with spikes that are holding the sandpaper. This sanding block is the bomb. I bought this in the middle of a boat gelcoat restoration job. I started with small black rubber blocks. I used wet sandpaper. First with 150 or 220 grit, then 400, then 500, then 800, then 1000, then 1200. I used several small pads for different grit paper because it was easier than switching paper between grit. With those little rubber blocks I never managed to stretch the paper and it always tore. About a quarter of the way down I was about to buy another of the little rubber blocks when I came across this block. I hesitated to buy it because the price was probably 4-5 times higher than cheap blocks. Man I'm so happy I bought this. The paper goes into the pad so easily. There is a clamp on either side of the block. Lay the paper on one side, pinch it, pull it to the other side and pinch it. The paper sits there nicely. Secondly, the block feels very good in the hand. The grinding zone covers a much larger surface. I would say I have probably reduced my grinding time by at least half and maybe more with this block compared to others. The paper is never torn and you can take out the paper and reuse it. You can never reuse paper from other pads. I also don't need multiple pads because the paper is very easy to change.