Preferred bleachers feature double foot planks on all rows.. Tip N Roll bleachersnbsp;are perfect for indoor/outdoor auxiliary seating requirements. Unit easily tips up on its casters for convenient storage. Framesnbsp;are 100%nbsp;welded aluminum angle. Seat planks arenbsp;annodizednbsp;aluminum. Seats 30 people. High grade swivel casters rubber foot pads will not mar your floors. Bleachers meet requirements of NFPA the Consumer Products Safety Commission standardsnbsp;. 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.