I am a DIY-er and using these on my new deck to fasten Cumaru hardwood.The screws seem to be of high quality and the black coating helps them hide in the holes instead of glinting in the sunlight. Out of a box of 1750, I think we have had one screw be bad but are only about halfway through the box.They have a trim-head, so for hardwoods, you can use them to face-screw when needed. I used a 1/64" smaller drill bit for face-screwing so that the head would have more holding power against the wood. You will need a different head shape for face-screwing treated or composite boards.I am using an 11/64" bit (instead of the recommended 3/16") to pre-drill for standard holes, and a 5/32" bit to pre-drill for face-screwing.I would not recommend using these on 1x deck boards. I am using 5/4 board for the stair treads and a "1x plus" (7/8") for the deck boards. The 5/4 installation seems okay, but on the 1x plus boards, the angled hole doesn't leave much wood on the edge and I'm slightly worried that over time it will cause splitting, especially in late summer. If I had used true 1x (3/4") deck boards, I don't feel it would be enough wood left to hold well. On 2x boards with the longer screws this system would be unstoppable.