When to change a helmet ?
The helmet comes under pressure in a fall or a collision. The outer shell is designed to prevent penetration (example: from a sharp stone, a horse's hoof).
The shock-absorbing inner lining, specially designed for this purpose, absorbs the shock by its deformation reaction.
So, after an impact, even if the outer shell does not look damaged, the inner lining no longer performs its role as shock-absorber. Only the outer part of the helmet will be active and the inner shock-absorbing lining will have a very reduced effectiveness.
How to take care of your helmet ?
If the outer surface of the helmet is made of Lorica® (a kind of synthetic leather), you clean the helmet (without solvents!) with soap and water using a sponge or a soft brush. This type of coating has been given a Scotchgard protection (3M product) against various kinds of stains. For painted helmets, a sponge or a soft brush is enough. Concerning the internal lining, GPA advises you to replace it with the Replacement lining.

When to change the inner lining of the helmet ?
This decision must take into account the hygiene and comfort aspects. You should get a Replacement in the following cases:
1. The internal lining of the helmet is dirty and/or worn out.
2. To guarantee the snug fit of the helmet on the head when the padding flattens out in places.
3. To adapt and/or optimise the fit of the helmet on the head with a choice of 3 different levels of padding thickness 
Why are the prices of GPA helmets high ?
For the following complementary reasons:
On top of the regulatory and safety aspects, GPA takes into consideration the aesthetic appeal and comfort of each helmet. GPA starts out with the principle that a helmet aimed at protecting the head requires considerable design input and research work in order to achieve the objective of maximum safety. And not the opposite: i.e. start out with the marketing and pricing aspects and then try to design a safety product aimed at protecting the head. GPA chooses only the best suppliers of raw materials.