5 inspection procedures are applied in our factory. 1) Material inspection before production line: to ensure all rubber sheets are smooth and pure. 2) Online inspection after assembling: to ensure no blister is on the boot also no skew on structure. 3) Leaking proof test after vulcanization: to ensure not a single piece of boot is leaking. 4) Inspection on packaging line: to ensure each pair is matching and no obvious defect after vulcanzation. 5) AQL2.5 sampling inspection after packaging: re-open packed carton to check defect rate for final products.