A Bell, the model of which I do not know, circa 2015. I had just fit clip-on aero bars but was still getting used to the transition between them and the flat bars, missed and went down at quick stop, hit hard enough to crack my 20+ year old helmet. Woke up to cop who just pulled up in car, said I was out about 30 seconds. I was ok, probably should have gone to hospital but head just felt a bit dull for a couple days, I took it easy during then and didn't bike, and was fine. Helmet definitely saved me from serious injury if not death. I ordered the Bell from Nashbar, $15 marked down from $50, good reviews, I've been quite happy with it except for the vents allowing the sun on my scalp. A couple years ago when a friend saw nice looking helmets at Costco marked down to $15, I checked fit (barely naked, no space for fleece hat) and bought one as a backup, I also like it because it's safety bright green. CPSC certified (do they have Snell certs any more?), but has same downside sun/vent issue.

My very first helmet, the Bell touring one with the smoked plastic brim, that was a lot of money early '80s, like $50-60 if I recall, they were pricey, but it was mandatory for a college class (they taught nothing it turns out, just had periodic rides, easy credit, but HEY, it got me started wearing a helmet ahead of the curve). After going down and seeing stars snowboarding, started wearing a helmet boarding and skiing, that old one which had worn loose by the '90s but fit perfect over a fleece hat or hood. I wear the current bike helmet for inline skating. If I'm sailing on a boat with a low boom, I wear the helmet, and a lot of sailing schools are now doing the same.

Now, helmets are common, and one need not spend that '80s price, especially in 2024 dollars, for a decent helmet. Simply one year old is gonna be at discount.

Y'know... I'll bet a cheap helmet, with the vents covered in aluminum tape, and if need be, NACA ducts cut in them for venting (notice below, not just cutting out that shape but the depressed inlet ramp), would be a lot more aero.

https://en.m.wikipedia.org/wiki/NACA_duct