... convolute foam,pocket spring(2.15mm diameter),can be replaced by Bonnel spring.compressed packed.Available size ... woven fabric,spring ...by ourselves.So,the price will be competitived.Warranty:Warranty is there to protect the ... quality control system, the spring we use can be compressed to 3.5cm and rebound to its ... you buy from us will certainly last 15-20 years, so we give our customer a 15years ...