The Master Lock No. 6521 ProSeries® Weather Tough® Shrouded Padlock features a 2-1/8in (54mm) heavy steel body to withstand physical attack and a 3/4in (19mm) tall, 5/16in (8mm) diameter hardened boron alloy shackle for superior cut resistance. Padlock is available with or without core with a choice of 16 Small Format Interchangeable Cores to match this padlock to your door looks – accepts standard SFIC OEM cores. The exclusive cover protects from water, ice, dirt and grime.