MRI Wheelchairs consist of materials such as Brass, Titanium, Aluminum and Plastic and have been tested and certified to pass through Pre-Screen and Pre-Entry door systems. This aluminum model should be ordered when a Pre-Screen or Pre-Entry system is in place as the standard non-magnetic models will set off an entry system because they are constructed of a high-grade stainless steel. Features: Sling style seat 250 lb. capacity 18″ – 26″ seat width 26″ – 35″overall height Quick release seat belt Retractable wheel locks Smooth ride, rust-proof hand rims 24″ diameter wheels, 8″ front casters