Diablo Steel Demon, 4" x 14/18 TPI , Metal Cutting Reciprocating Blade, For Thin Metal, Delivers 4 Times The Life Of Standard Bi-Metal Reciprocating Blade, Features A Hardened Tooth Technology For Superior Durability In Extreme Applications Perma-Shield Coating For Reduced Heat & Friction & Dual Tooth Design For Better Control, Bulk.