I use the EAR brand 33db ones (foam dispoasable, dirt cheap when bought in large quantities). They fit me comfortably, and make a serious reduction in noise (and on a bike with lots of tingy sounds like most 250s, they make the bike sound better to me
I use them any time I’ll be travelling above 40mph. Which is pretty much every ride. I only leave them out if I’m planning a short loop through city streets.
If I’m on the bike without them for an hour, I feel fatigued. With them I feel significantly better. It is amazing how draining noise really is.
Also, I reuse mine. I can get about a week of commuting out of one pair.