Tread WS-1 A basic smooth steel plate tread, it can be used as is. Other variations include hardwood overlays or particleboard for carpet upholstering. Pan treads can be recessed to any depth specified to accomodate slate, marble, rubber, or carpet inlays. In this design, the Steel edge acts as a protective nosing and prevents the inlaid material from chipping or wearing excessively. An abrasive non-skid surface is also available.