This gadget has been residing in the back of one of my tool drawers for years. That tells you how often I use it. To be fair though, the blades seem to be more effective on white button mushroom than on the tougher crimini mushrooms that I favor.
The mushroom slicer can also be used on hard boiled eggs, although there is a version with an egg-shaped bottom that can be easier to use.
Both versions are easy to find in the kitchen department of many stores. I purchased this one years ago, but I’m sure you could buy a mushroom slicer for less than $10.00.