I've never really heavily filed my nails due to the damage I endured when I once had them done in a nail salon, my poor nails bled down one side and were incredibly sensitive so I've been scared to file them for the longest time until I tried these glass files and erm how pretty?! The glass is so much gentler yet it does the same thing as a normal file, the grit on the board is really fine so can take a little while to file down but I don't generally use a file to take massive amounts of nail off so this works brilliantly.
I've used a glass file before and it was so cheap feeling and thin I thought it would snap and it did after dropping it, you can certainly tell the difference between this and a cheap one off eBay. Unlike normal emery boards these take a lot longer to wear down so it may be a bit more money to pay out now but it's worth it.
I got the large size that's coloured and has crystals on it and a smaller one that's perfect for your handbag and fear not, the glass is toughened so they're super durable and safe.