Alder Stair Tread – 984 Description Description A98448 – Alder tread for interior stair systems. 1″ thick x 11-1/2″ from nose to back. Available in 48″, other sizes available by special order Call For Quote $42.71 Interior Tread View Product Catalog Quantity Add to list Become a member:Email firstname.lastname@example.org. SKU: A98448. Category: Stair Parts.