I have tried the drills that have batteries in the body of the drill
And while they don't seem to be bad, they just don't have the power that this one does.  I'm thinking it has to do with the size/strength of the battery in the drill's attached power supply.  While I do use this for my fingernails, I am using it more for my toenails and feet.  Toenails are thick and tough and I have trouble cutting them well even with good toenail clippers so being able to file them a little at a time is much easier.  Also, I have some very hard, thick skin on my feet and "grinding" that skin down is much easier that using a foot file.  This is a wonderful nail drill that's not just for nails - sturdy like a workhorse, it will make short work of messy nails or hard, callused skin.
Rating: 5 stars