I will wholeheartedly endorse this product at this price - VISM AR15 Lower Receiver Vice Block

I have routinely installed and uninstalled receiver extensions since the mid-1980s, primarily using wonky homemade jigs and such. I recently decided it was time to purchase a proper tool for the job. I read several reviews that didn't speak highly of this product but, having used it for the first time today, I'd say it does a very good job. Alignment is perfect, and the time to remove the old extension and install the new was probably only a third of the time that I would usually have taken without this tool. Would there be better options for a professional police or military armor? Probably. For your average guy working on his own rifles at home, this is definitely sufficient. I can't imagine that even as much as I change things around that tool this won't outlast me. I don't really have any complaints but I do have one warning. While the manufacturer does put thin strip of some sort of material inside the clamp that goes around the extension tube itself, it is not enough to protect the anodizing. Out of sheer curiosity I removed the old tube without using additional protective material of any sort and it did leave some abrasions in the anodizing. When I installed the new tube I wrapped it with commercial grade 2 in masking tape and also placed tape around the pistol grip mounting lug. Having done that there was no damage to the finish. So yeah, all said I'd highly recommend this for home use.