... which are 15`and 21`ft.2.Suitable in stadium,training field,racing track etc.3.Seat options:Aluminum plank,Vogue ... 7.5`, 15`, and 21`ft.2.Suitable in stadium,training field,racing track etc.3.Seat options:Aluminum plank,Vogue ... . All styles available in portable, permanent, or surface mount installation. motor movable telescopic bleachers