Noise level (decibels) is not linear. The difference in 20NRR and 33NRR is significant. ie 110Db -20 vs -33. I use Howard Leight Impact Sports when I shoot outdoors and add foam ear plugs when I'm at an indoor range. I'm hard of hearing, but I can hear conversations even with the ear plugs with the Impact Sports. I have a another pair of Howard Leights that are too big to use the long guns and they are heavier. I don't remember the model- may be the Pro, but I don't like them. Also have a pair of Peltors that I didn't like, can't recall the model, but they were about double the price of the Leights. Have a couple of pairs of Caldwell electronics I bought to lend anyone who comes along with no protection. And several pairs of kid size passive muffs along with kids eye protection for the grandchildren. I almost bought a pair of the Walker Razor behind the electronic ear plugs, but I tried some on at the Cabela's in Fort Worth and couldn't keep the plugs snugly inside my ear canal.