These extensions make it very easy to dig a suitable hole for a standard 8ft rack. A power head with a standard auger allows you to go down about 28 to 30 inches depending on how close you position the power head to the ground. As stated in the Xtremepower Single Bit Guide, it is best to use a standard bit to drill the hole, then add the necessary extension to dig the hole to full depth and make a second pass. Tip: use the SHORTEST extension that gets the job done. At first I used a 12" extension to get the full depth, but you can get a tremendous amount of extra bottom weight and friction from this. The 8 inch extension did the job perfectly, with a lot less "weightlifting". They appear reasonably well made and come with a pin and open end wrench (which I immediately replaced with a clutch pin clamp). These extensions make your drill more durable. much more useful, at a reasonable price.