Worthy
This is a good device for removing calluses. I wish it had a little more power, hence the 4 star rating, but it does the job, albeit slower than I had hoped. I thought the price was/is very reasonable given the competition, but I was hesitant to purchase given my inability to locate replacement rollers, but I bought it anyway. Afterwards stumbled into 3 replacement rollers for less than $10, incl. shipping (albeit 25 days from China).  Search for km-2502 in any reputable search engine - look for ali express.
Rating: 4 stars