I got mine at the dollar store, but it's like this one. Essentially it's kind of a guillotine for eggs. You lift up the top and place the egg inside, then there are evenly spaced lengths of wire that slice through the egg when you press the top down resulting in perfect, round slices. Lift and rotate the egg 90 degrees, put it back inside, and you can slice it into perfect strips for egg salad! I also use mine to cut mushrooms, strawberries, babybels and goat cheese. Not a "necessary" tool by any means, but useful and quick if you enjoy sliced, boiled eggs like I do. :)