Hey, sorry it took me so long to respond. I was originally trying to remove this cap because we had a septic system failure and after the tank was pumped out the plumber snaked the line from the outside (in the tank) in. He shoved some of the solids back into the clean-out area and it ended up working its way back under the opening of the main line. I ended up using a garden hose with a nozzle attachment to spray a jet of water from the outside in and managed to remove the pieces that the guy didn't get. Shouldn't he have snaked the line from the inside out so that he could actually see that the line was clear? By the way, the outfit I called that day was Mr. Rooter, which is a franchise, and they ended up being a bad company to do business with. They tried to collect money on the septic system job without getting the proper permits or doing any initial testing of my soil. That is another story but the clean-out was only a smallpart of it.