quality reference:
2.Foam pad: EPE,closed-cell foam that will not absorb water,mildew or lose shape 3.Pad: PVC(500D,500D) fabric
4.Tubes: galvanized inside and outside
5.Springs: super high-srength galvanuzed
6.Harness: the same to the car harness
7.Elastic rope: it is rubber inside and outside