I found this little gem in one of my all time favorite shops, The Refill Shoppe, in Ventura, CA. This little glass nail file is perfect! It's easy to disinfect (which you should do frequently), has a point that's great for getting dirt out from under fingernails, works beautifully, and comes with a cover. They have three sizes available; I have the smallest size because I like how easy it is to slip into a purse pocket when traveling.
Plus, The Refill Shoppe has an awesome rewards program so definitely sign up! They have an online shop too!