This is SmartKey Cylinder that fits exterior double cylinder deadbolts. With Kwikset SmartKey you never have to worry about an intruder finding lost or stolen keys again. Kwikset prides themselves on creating ANSI Graded bump guard protected high security door hardware you can trust to be drill and pick resistant. Re-key your SmartKey locks as frequently as you wish while maintaining the highest level of security. This cylinder allows you to turn your Kwikset cylinders into Kwisket KW1 keyway with SmartKey Technology.