Helmets
Not wanting to look like a mad man who lost his bike isn’t the only reason that we climb with climbing specific helmets. Climbing helmets are actually designed differently to other helmets.
Types of helmets
Hard shell: These are the classic shell and are made out of a hard plastic. These helmets provide the best protection from falling rocks and have the highest ballistic rating. The downside is that they are heavier and in an age where every gram counts they are slowly losing their place in climbing.

Foam/Soft shell: These are the lightest helmets on the market and are made from a high quality polystyrene. They are less robust but meet UIAA guidelines.

Hybrid: Finally we have the hybrid. This helmet is like the foam shell but has a thinner hard shell on top. This means you get the benefit of the hard shell but the helmet is still light.
These are the most common types of helmet you’ll find.
Fitting a helmet
1. You want it to be snug on your head. You want to be able to shake your head without the helmet coming off.
2. Make sure your forehead is not exposed.
3. Make sure it can’t fall down and cover your eyes.

What to buy?
Black diamonds half dome helmet is a good buy for beginners. It will suit all your needs, has a good online rating and is great value. If you want to spend a bit more then look online there are lots of great deals.

Personal choice
Personally I like the petzl meteor and would spend the extra few euros.
For a more in-depth article check out this outdoorgearlab article.
https://www.outdoorgearlab.com/topics/climbing/best-climbing-helmet/buying-advice