I received a set with a CNC machine first and have been using it for 3 months. I cut something with them almost every day, mostly plywood, and they are durable. The bits are still in great shape and cut cleanly. I know they will wear out eventually because I use them so much, but so far they show no signs of slowing down. I was so impressed I ordered a second set as I saw they were very good value for money on Revain. The kit contains most of what you need for a CNC machine with 1/8 collet. This does not include the "V" incisors.