Kioti website lists 9,12, 16, 18, 24 & 36 as standard sizes. I知 looking for one good all around size as a starter bucket I have zero experience to go on, the soil here is pretty rocky small, large you name it we致e got it. There is clay out back in the field where it have some water drainage issues I haven稚 dug much at all in the other areas around the house.I need to do some run off control ditching, and moving some big stones back onto stone walls , I want to run an underground conduit to an out building, and I知 sure many other things. If I need a specialized bucket I could buy it at a later date when the need presents itself.