I keep hitting rocks trying to put in fence post. I got tired of trying break them be hand. After finding out how much it cost to rent a jack hammer with a air compressor by the day, I started looking for a electric jack hammer. I got the Stark 2200 watt demolition hammer, it looks like the same unit with many different names, from E-bay. It has a parts breakdown in the back of the manual, all 10 pages, that said it was a model HM 1306. I tried a search on the internet for HM 1306 and found that Makita makes a unit with the same number and with very little difference looks the same. I also found a parts list for it and checked several parts and they all matched be the item number and the part number. At under $200 it cost less than 1/4 of what a Makita does. I am not saying they are the same inside but it looks to me like they could be the same. Take a generator with you and it is a lot easier breaking thru the rocks. After using it a few times I'm happy with it for the cost. Do your research before buying it could save you a few hundred dollars.