Though it was very uneasy thought that it was OK at the beginning with 3 blades, the price is also cheap, the hold is solid, and the place to change the size is also very good. I found the hole as I thought very easily, regardless of its appearance. Strongly improving points, it is better if there is a hold on the disk side so that it can be loosened easily when loosening the bolt at the time of storage.
Hold was solid, size was changeable, of course the hole was also opened. (The previous other company's products could not be opened and it got broken.) If you point out the improvement points, when you change the size, loosening the nut loosens the point that the blade comes off.