You're doing gods work, people really need to understand that tinnitus can and will happen to you if you go to enough shows without hearing protection, I have definitely developed some, but earplugs have really helped mitigate more damage. Also if people want some extra cheap quality earplugs I recommend these a lot of people prefer them to the etymotic ones. If you lose them its a very cheap reorder too.
Honestly I'm not sure of any specs, you can spend as little as $15 bucks on a pair or as much as $75. Like I said mine were gifted to me and they don't have a brand name on them but I don't think they're a particularly expensive kind.
Here's a cheaper pair I found on amazon. And yes these would be different than the solid foam ear plugs I would use for sleeping.