You have chosen a good subject for a technical study, and have photographed the drill bits well - excellent rendition of the texture of the brushed metal. A separation of the bits would, I feel have made for a stronger composition though.
Drill bits were on my list of items to consider. I hadn't thought of putting them on a mirror. That's an interesting choice that works ok (be better if the mirror was clean - sorry, couldn't resist). Something about this still doesn't present optimally I'm afraid. Maybe with some space between the drill bits, or only three and have the variance in lenght a little more pronounced? As is, they clump together somewhat. JMO of course. Good luck in the challenge.
*not voting as I'm in this challenge-just commenting since I've seen requests for comments in the challenge thread*
Overall this shot is very nice. I like the composition, color(or lack there of) and clarity. I think that all the sensor dust and those white spots on the BG really take away from the beauty of this shot though.