Review (5/5): Great!
I teach high school and need to wear a mask for 8 hours at a time. I combined one of these beneath my homemade drawstring masks and I'm good to go. It's comfortable (as comfortable as a mask can be anyway) and I can still speak clearly and be heard by my students and colleagues. Given that it can be sanitized daily, I've given away probably half of mine to coworkers who have trouble being heard.