I posted this same problem in the shower thread but didn't get a lot of response. It was recommended that I post it here too. I have a single handle shower that was doing a lot of sputtering when the hot water was engaged. I did some research and deduced it must be the cartridge. I took the handle off and found what you see in the pictures. I'm trying to figure out how to remove what I need to remove here. I'm very new to plumbing. Anyone ever dealt with this type of component? Any information is very much appreciated.