CamCam Kapok Extension Mattress 90X40cm NaturalMattress for the Harlequin Junior bed. The mattress is made of 100% Kapok. Kapok is a natural, organic and sustainable material from the Kapok tree, also known as the Silk-cotton tree. The material has great characteristics, is hypoallergenic, breathable, and antibacterial. Kapok is the most breathable natural fiber in the world. It contains 80% air, and is 8 times lighter than cotton! A natural bitter substance inside Kapok makes it antibacterial and impossible for mites to live in.