Box stair Retreads are made of .625 inch thick solid wood slabs with a traditional nose profile that simulates a 1” thick tread with cove molding applied to the bottom. Traditional Retreads are available from 36 inches to 96 inches in length. Box Retreads are used for remodeling an existing staircase. The staircase must have closed stringers to use box Retreads if there is an open stringer on one or both sides you will need a return Retread. This product will not cover dimensional lumber treads, a new riser will need to be attached to the existing riser of the staircase to hide the bottom of the existing dimensional lumber tread.