Firestone UNA-CLAD UC-6 Double-Lock Standing Seam Roofing Panel utilizes the proven seaming process of Pittsburgh Locking in conjunction with the floating action of a concealed clip assembly. This design allows for expansion and contraction caused by natural elements to provide a virtually leak proof roof with exceptional uplift ratings. UC-6 Roofing Panels have the ability to span open purlins. This system may qaulify for a 30-year Platinum Warranty.