Preferred bleachers feature double foot planks on all rows..Tip N' Roll bleachersare perfect for indoor/outdoor auxiliary seating requirements..Unit easily tips up on its casters for convenient storage..Framesare 100%welded aluminum angle.Seat planks areannodizedaluminum.Seats 20 people.High grade swivel casters & rubber foot pads will not mar your floors.Due to constantly changing specifications, please check local building and safety codes for compliance..WARNING: These lightweight units are easily tipped up for rolling by any responsible adult. However, if tipped up outdoors, extreme caution should be taken in windy conditions. Multiple adults may be required to control the unit... .