this spring mattress inner spec as below: knitted fabric,memory foam,high density foam, spring ... F,Q,K. can be compressed 1. High grade knitted fabric, 650g/m2 2. Quilted foam: 2cm thickness, ... springback function when the body by the mattress.7.To prevent your waist and knees ... insect-resistant ventilation design, ensure the internal mattress cleanly and sanitation.15.imported materials from Belgium ...