Technical specification: blow molded double-walled high-density polyethylene (HDPE) plastic seat. Plastic formulation is fully compounded with ultra-violet inhibitors prior to the manufacturing process. UV inhibitors are added at a rate to ensure no significant color or plastic deterioration for a period of 10 years.Minimum wall section thickness is of 3.5mm at the extreme corners of seat. The actual seat width is 420mm, the seat depth is 450mm, weight: 2.4kg per seat. The leading edge of the seat is to include an angled recessed location for seat number.and there is high quality steel under the back of the seat to protect the seat and avoiding damaging while frequent using. The mentioned various advantages of hollow chair come from the material itself and the double-walled structure: 1.Suitable to various climate: The HDPE material compounded with ultra-violet inhibitors works very well under various climates from 60-80 degree of centigrade. Our stadium chair has been installed in Micronesia of Equatorial zone and Haerbin of north China; 2. Acid and alkaline resisting: The HDPE material itself has fine chemical stability of acid and alkaline resisting, it even could endure 24 hours in oil of vitriol or muriatic acid at 100 degree of centigrade without changing it performance. So it suits well to the environment of acid or sea-shore area; 3. Static electricity resisting: The dirt could be adsorbed to the chair that will blot occupiers clothes as well as dumb the seating. Our process of static electricity resisting prevents the mentioned disadvantages; 4. Abrasion resisting: The whip of the HDPE material is excellent; 5. Non-sticking with water: It protect the seat from blotting of juice or sewage; 6. Color adhesion: Additives of color adhesion are added to ensure no significant color or plastic deterioration for a period of 10 years; 7. Security: All edges are designed round to avoid hurt to occupiers.