1-20 SPECIAL THREAD CARBON STEEL HEX DIE. CARBON STEEL HEX DIES ARE USED TO DRESS OVER BRUISED OR RUSTY THREADS, THEY ARE THE MOST COST EFFECTIVE RE-THREADING TOOL AVAILABLE. NO SPECIAL HOLDER IS REQUIRED FOR THIS TYPE OF DIE, AN ADJUSTABLE WRENCH, AN OPEN OR BOX END WRENCH, OR A SOCKET WILL DRIVE THIS TOOL. THEY ARE IDEAL FOR MAINTENENCE IN THE SHOP OR FIELD.