Product Dimensions: Length (190.5 cm), Width (167.6 cm), Height (10.2 cm). Primary Material: Foam. Warranty: 1 year on product. An extra firm coir mattress is a type of mattress that is made of coir or coconut fiber. The coir fibers are compressed and molded into a dense layer, which provides firm support to the body. These mattresses are known for their durability and ability to maintain their shape for a long time. The coir fibers used in these mattresses are usually treated with natural latex to increase their strength and durability. The latex also helps to make the mattress hypoallergenic and resistant to dust mites and other allergens.