The one size fits all mango slicer fits only one size of mango. If you always buy/produce the same sized mango that happens to fit the size of the slicer, fine. Otherwise, best to just use a sharp knife. I do not like a serraded knife for my mango slicing. I also prefer a longer blade which does not have to be razor sharp. In fact some slight dulling of the blade can save some nasty cuts when you get into a mango cutting frenzy.
Harry