National Hardware Steel Single Box Rail Brackets 300 lb (Pack of 10).National Hardware provides the Track, Hangers and Sliding Door Hardware components needed to create your own barn and commercial sliding door system. the advanced designs are made of galvanized steel in round or box rail and come with heavy duty hardware for easier mounting and smoother operation. Used primarily for exterior applications, they are also ideal for adding an industrial look to any contemporary or rustic interior. UPC: 038613104334