We bought these about a year ago for our 4 year old boy with high functioning ASD and sensory processing issues (he's very afraid of loud sudden noises).
Our occupational therapist advised us not to overuse them as he has to get used to dealing with sounds in a normal environment like a parking lot, but these were great for forth of July this year. He went from "These Fireworks are upsetting me" to "Time for MORE fireworks!!" =-)
These are durable enough and are worth the price.