I used to Groom Dogs in the 70's and I am STILL using my Oster Clippers and they STILL work fine on my Yorkie for 3 years now. I used to cut my Son's hair and my Husbands hair with them also for years in between and trimmed up our Golden Retriever. I have never had them sharpened. I will get another pair of Osters when the motor wears out in this one although they are expensive, they are well worth it. They don't have the Model that I have anymore after all these years but they have served me well.