Efficacy against mosquitoes and the physical strength of Olyset® nets are guaranteed for five years. Sumitomo Chemical cannot offer this guarantee if the net has not been used or cared for in a normal manner. There should be no extended exposure to sunlight or other heat sources and no washing in aggressive or alkaline solutions such as bleach. Please follow "Washing Instructions" as indicated. Sumitomo Chemical cannot be held responsible for physical damage caused by burns, tears from sharp objects like nails or damage caused by animals chewing the net.