Is it the Emjoi Micro Pedi? http://www.boots.com/en/Emjoi-Micro-Pedi-rapid-hard-skin-remover_1245237/ If so, I can thoroughly recommend it. I have tried everything and apart from visiting a chiropodist every other week, this is absolutely brilliant. I've only had mine a week or so, but I have to say, I love it.
Should add, this isn't a grater type thing, more of an electronic sandpapery thing. It's really good though.
However, my favourite of all time was made by WAHL and they don't appear to list it any more, it was called Foot Care. Electric or battery, it has a cartridge like an abrasive fan belt.
Absolute bliss. After using it, I can tiptoe through the tulips no problem.
It looks like it is the same idea. I found info on the WAHL one, and it is discontinued. They used to sell spare cartridges (basically a new abrasive fanbelt.) I still have one unused left, I am pleased to say. I love it because I much prefer electric to batteries, and this runs on either.
It is very addictive. My husband walked in the other day and said, 'you are meant to have skin on the bottom of your feet, it helps you walk'. It was hard to look annoyed when I was laughing so much.
lol the wahl one that jean is referring to sounds exactly the same as their dog nail grinder, not sure if the dogs would appreciate me borrowing it though.