hard top

It is used for cars and the type of roof they have, the opposite is a convertible as it can change its roof and is not a constant hard top.

"I prefer a hard top car to a convertible"

"I don't think you know what a top is Bob"

emergency hard hat

A construction type hard hat kept in the trunk of an automobile for shit emergencies allowing wearer "no questions asked" free access to tens of thousands of Porta Potties nationwide.

When I wear my emergency hard hat,I can use the Porta-John at any construction site and nobody gives me a second glance.