10-Piece Hole Saw Kit for Wood | Durable Carbon Steel Power Drill Hole Cutter with High Precision Cutting Teeth – Woodworking HCS Hole Saw Kit for Wood, PVC, Plastic, Drywall

just what I needed for a project

I tried to use the largest 2.5 hole saw to cut through 2 of wooden floor from my crawlspace towards my distribution panel to run some conduit. The hole in the saw which normally has two flats to drive it, rounded out so that it no longer works (see picture for comparison of good drive hole vs bad). As the largest hole saw in the pack this is the most torque demanding. However the saw was evidently insufficiently hardened for the task, hence the 1-star for durability.