I used my DeWalt DCD996 drill on low speed, (1), and chuck torque at 8. Cut 22 holes with 2 11/16" and 10 holes with 4 1/8" hole saws through galvanized steel purlins. These hole saws cut through the purlins very easily and do not show much wear, still sharp as new. Did break 2 pilot bits. Am highly impressed and happy with this hole saw kit.Note: The hole saws will catch when cutting through. Caution for kick back on drill.You get more than enoughOnly hope saws we buy for our electrical business.Has all of the required pieces for electrical needs with good quality.Lenox Tools has the best product for hole saws. This will last a lifetime. I do not know why they call this an electricians kit because it has sizes up to 4 inches which is good for the majority of plumbing needs. High quality! Great price. Well worth it! You may have to eventually replace a saw blade if you use it on metal or tile, but for wood they do not get dull. Lenox has engineered this for useability. Easy change out and plug removal. This is what the professionals use at almost twice the cost.I have used many if not all of the different hole saws available to me and these are as good or better than any of themVery nice set of saws. Box is well made and tough. Its pricey, but you get what you pay forLove Lenox, best hole saws on market.This is a high quality hole saw set! Very happy with the purchase! We use hole saws a lot in our mechanical contracting company and these are some of the very best you can buy!Pour l'instant je ne m'en suis servi que dans le bois mais c'est bien du lenox, top qualité, pas de problème.センタードリルが曲がりやすいです