Knowledge: All medicines have an expiration date just like food. It is located at the bottom of the medication container. Also, all helmets have an end date and must be replaced with a new one as it is illegal to use out-of-date on the road.

Conversation:
Hi, I am in a motorcycle club! We annoy other drivers on the road!
Sounds interesting. Is yout club organized around a make or brand?
No it is not. Do you know if helmets are really protective?
Well, I know that there is research into what is protection degree that a helmet offers if an accident occours.
I see, is there an expiration date on it? I heard but never saw.

Response: Well yes. All helmets have an end date and it is illegal to use out-of-date on the road so it must be replaced to a new one.