Earth Therapeutics Glass Foot File - Durable Salon-Grade Tool with Finely Abrasive Surface for Effortless Callus Removal, For Wet or Dry Use, Compact and Easy to Clean

I think it needs to be seen by a doctor because it started from a scratch. Otherwise I'd recommend he use glycolic acid on his arms after bathing, then moisturizer. Also, I got a glass foot file and it's the best foot file I've ever used. https://www.walmart.com/ip/5164703874?sid=8a25ace3-9932-40ec-b086-1e66ddece657