They work great. I doubted they would work that well given the low cost. using a sledgehammer was not effective. I've split about a dozen boulders with it and am very glad I bought it. A good demo hammer makes the job very easy. I replaced the cheap rock drill bit with a 1 1/8" demo hammer and made drilling holes much faster. It should be noted that the 5/8" tool has a hint for drilling a 1/2" Lochs included, which is incorrect. To install a 5/8" tool you must drill a 5/8" hole. You may think this is common sense, but the way things are labeled, I did I believed the note and drilled a few 1/2" holes before the tool arrived and then I had to go back and drill new 5/8" holes.