Not enough - AXIL Ghost Stryke I Hearing Amplifier

These seem to cut noise level at the firing range significantly, but so far I don't think i'm willing to trust them to prevent hearing damage for all day use. I think they are fine for field use with only occasional shots fired, or for intermittent protection when shots are fired on the range and your muffs are not covering your ears. I think I will wear them along with my muffs. The other thing I noticed was that if the whistle signal to begin firing is loud enough or close enough, sometimes they activate and cut it out.
Optics planet was great with a very good price and fast shipping.