Had purchased the r300 dct disc cutter not realising you need the r300+ for the water supression system as its not very clear they don't do a retrofit supression system both machines look the same. I have used the water supression to cut concrete blocks and it does keep the dust down very well the drawback to this is you get wet with the slurry produced ,maybe would have been an idea to fit some sort of rubber splash guard . After cutting quite a few blocks the button on the start handle has started to stick on so the machine does not always stop when you release the power switch. The cutter defiantly cuts concrete and concrete blocks very well