Chicago - 3 1/2” auger - Needed to plant 2” square steel posts (10) for small fence on utility parkway. Needed 12-14” depth through hard clay, roots & rocks. I used a standard Makita 18v hammer drill (XPH12Z). It worked as intended. Here are some tips… 1 - I sharpened the blade edges with angle grinder/flap disk. 2 - I used lower speed & hammer drill settings. 3 - I didn’t try to force through obstructions, I ‘pulsed’, on/off & tried different angles to unseat larger rocks, roots. 4 - Remove broken up soil frequently. 5 - loosen your grip. If auger grabs & stops you’ll end up with a sprained wrist if you don’t let go. This is not a Pro/industrial tool, but if used correctly, with patience, it’ll do its’ job as intended.The square shaft at the drive end that fits the drill is a problem. Drill chucks have 3 jaws not 4. The auger loosened and fell out several times. It did work well with an 1/2 inch heavy duty ac powered drill. Battery powered drills do not have sufficient torque. I also watered the soil the day before using the auger.Smaller one works better with hand held drill. Larger one is good to enlarge the hole after.Obtained to help dig for pole base concrete. Works very well in hard compacted clay soil. Used in old style drill. Does some good work!The auger works well in our sandy loam.Never arrived the first time, amazon send my other one so quikly, good productThese have made planting our flower bed very easy. Quick drill and the hold is made. Note, I have a heavy duty electric drill, my small battery powered drill tended to have a problem with them so got out the heavy guns and they worked great.Did what I wanted!Absolutely useless, even a small stone in the soil removes the bit from the drill, I tried with different drill machine but that again wasted time as wellIt ok but could be better qualityGreat product. Digs holes well. So much cheaper than anywhere else. Great quality, will save you so much time and from pain in the garden.