I just got these a couple weeks ago and have used them once or twice. Even so, they have performed outstandingly. One job required that I cut out the middle 5/8" of a piece of 3/8" thick channel. The mill cut through the full dimension like butter. This was a dry cut at 425 rpm and I expected that the tool might overheat but it took it just fine. The other job was elongating a 5/8" slot. Again, the steel peeled off and the tool stayed nice and cool. I can see that these cutters are going to do a lot of good work and be one of my first choices when setting up the mill.The four stars do not reflect the quality of the bits, only that I have only used the 1/4" bit in a trim router to clean up some dados made with a cheap straight bit. The bit worked well in soft wood and cut clean. I purchased 3/8 and 5/16 collet inserts to be able to use two end mills that are not 1/4 or 1/2 shanks. I do not own a CNC or milling machine, and plan to use them with hand held routers in home made jigs. So far they are doing what I need, cutting cleaner and cooler than common straight cut router bits.Me agrada es muy útilBeen using these for a while now and even though I'm just a beginner they are holding up fairly well,have been cutting mild steel and they seem to hold an edge pretty good, they are also very accurate, I measured them and each one is consistently half a thousanth of an inch under their stated size. Will definitely buy some more as I've already broke 2 due to my inexperience.I've been using these on mild steel.50mil cut full width no problem in 1/2 inch end mill. There is a lot of tool deflection if you try to take a 200mil cut (at least 10mil deflection).1/2 inch full height side milling 20mil deep no problem.What-you-see-is-what-you-get cheap Chinese tools written in Asian all over the package haven't used them yet not sure when I'm going to but they look like they would do a decent jobGreat product. Ordering system was so easy to perform. Shipping was on time, packaged correctly. The cutter have work precisely as expected. Will look forward to doing business with them again.These are ok bits, they cut fine so long as you don't over-speed the feed rate or spindle rate, just don't hold an edge as long as I would like, but you get what you pay for.I like it