... life best and must choice Excellent Years Luxury Mattress Healthy and beauty, your 1\3 life best ... rate of spring more than 75% for each mattress.1,String of spring ( help to connect the ... independent spring, so that to make the mattress bear the body and make the balance for ... tied up around the springs, help to confirm the whole mattress ) ,4, Outside material ( knitted fabric,knitted cotton, ...