Chup will boast that their "Life Long" socks might possibly be the last socks you buy. Knitted with Invista's highly durable material, Cordura®, which is 7 times as strong as normal yarn and gives amazing durability of 6 to 10 times that of ordinary cotton socks (scientifically tested and verified). These socks include Cordura yarn from top to bottom, not just in the heel, toe and sole (the minimum for socks to be able to use the Cordura name). Subject to abrasion testing for wear, to pass they must survive 500 times - Chup's "Life Long" socks clear the abrasion test more than 30,000 times. So they may not be indestructible, but they do wear extremely well (as Giles, their biggest fan, will testify).