Choose a junior mattress that is of sufficient density

A child will probably use his junior bed until he is 18 years old, his weight can increase strongly in adolescence, which is why we recommend a minimum density mattress 25 KG / M3.
The best is to aim at 28 KG / M3, which is an ideal density. This corresponds to a rather firm mattress.

Pay attention to the thickness of the junior mattress

On a junior mattress, the right thickness is between 16 and 20 cms. Beyond this, it may exceed the bed frame. On the other hand,  below this thickness, it's too thin and the mattress confort will not be perfect.

Prefer Junior mattresses made with fabrics that breathe.

A child sleeps much better on a junior mattress made of breathable fabric (Tencel or Coolmax type), rather than a mattress whose cover (also called ticking) is made of cotton or polyester fabric.
The fact that the cover of the mattress can be removed is also a plus, indeed it will be more easily changed in case of glitch.

Choose a good mattress protector

Avoid PVC mattresses protectors that do not let air circulate, to protect your mattresses.
Always choose a breathable mattress protector with a polyurethane membrane.

Your child will spend much more pleasant nights with less perspiration.