Yes! Choose either tool, depending on what kind of texture is desired and how much work you want to put into preparing the batter. A box grater can be used in several different ways. Use the large grater side with the widest holes if you want more of a shredded potato look. Although, the onion will still need to be done on the fine side.  To achieve a finer texture, use small shredding holes. A small shredding side can be used for both, potatoes and onion. If you want the finest texture, use the rough side with holes that stick out. Those will create the finest texture.