12X24 COBALT BLD BULK 10PK Century Cobalt Bi-Hard Blades Offer An Unique Design That Stays Cooler, And Remains Sharper While Cutting Harder Materials Like Steel Or Other Hard Metals. One Piece Construction, Cannot Edge Strip And Avoids Any Of The Weld Line Problems Associated With Bi-Metals Blades. Cobalt Bi-Hard Hacksaw Blades.