From the box they appear to be of good quality. I only used each bit once for 5 minutes as a performance test compared to other brands like Bits&Bits and the like. The cut quality is currently ideal for milling machines and hobby CNC machines. I can't comment on their durability as they haven't been used enough to tell, but I'm still impressed with the value for money. As a vet I try to support other veterinary businesses and if the lifespan of the bits exceeds what I can get locally I will continue to purchase these bit sets from Foos. Business owner, thank you for your service.