These work well. I don’t know if they work well enough to justify the price difference between them and Surefires, but they are a lot more comfortable.
Another user of the EP3’s here. I have not used them indoors but I have used them outdoors with my pistol and rifle(m14), and an m16 range at work with no problems. I was kinda worried at first but was quickly glad I bought them. I would though if used indoors double up though. (sighs), I still need a good pair of ear muffs though.