Review on JelBo HSS Step Drill Bit Sets For DIY Woodworking And Metalworking: Hex Shank, Multiple Hole Sizes, And Impact Driver Compatibility (3Pcs/Set 4-12/4-20/4-32Mm) by Don Kishore

I picked these up because I was tired of going back and forth between SAE and metric measurements on larger builds. The 3 different step sizes were a draw to me as well because I cannot always get the drill in from the back side to clean up the holeThey are only "HSS" so I figured they would work on plastic which is what I normally poke holes in. The pretty gold coating is irrelevant at the rpms I use.No matter what feed speed, rpm, and what type of plastic they always leave a bad burr in the hole. Reguardless of the step size.I'm not going to return them as I never expected them to last that long being offshore "high speed steel"While these are still around, I will shop for more cobalt type which I've purchased in the past. Those survive metal much more. I dont suspect these will survive even aluminum.Plastics i have used them on: polypropylene, medium density polyethylene, and high density polyethylene. The holes were clearer on HDPE but that was a limited trial.If you have a small job, these may work. A bigger job bite the bullet and buy better ones.I increased this review one star.The seller was pretty persistent in trying to reach out to me to correct my dissatisfaction over the drills. However the first couple of emails weregarbled some how, the last email couple were pretty clear. I'm not sure what happened with the first emails.They offered to refund the money for the bits and explained that they were working already trying to find a better drill based on my review. Therefore, it appears that the sellers actually care about satisfaction. I consider that worth an extra star.