The KYK-13 Electronic Transfer Device is a common fill device designed by the United States National Security Agency for the transfer and loading of cryptographic keys with their corresponding check word. The KYK-13 is battery powered and uses the DS-102 protocol for key transfer. Its National Stock Number is 5810-01-026-9618.

Even though the KYK-13 was first introduced in 1976 and was supposed to have been made obsolete by the AN/CYZ-10 Data Transfer Device, it is still widely used because of its simplicity and reliability.^[1] A simpler device than the CYZ-10, the KIK-30 "Really Simple Key Loader" (RASKL) is now planned to replace the KYK-13, with up to $200 million budgeted to procure them in quantity.^[2][3]

• P1 and J1 Connectors – electrically the same connection; used to connect to a fill cable, COMSEC device, KOI-18, KYX-15, another KYK-13, or AN/CYZ-10.
• Battery compartment – holds battery which powers KYK-13.
• Mode switch – three-position rotary switch used to select operation modes.
  • "Z" – used to zeroize selected keys.
  • ON – used to fill and transfer keys.
  • OFF CHECK – used to conduct parity checks.
• Parity Lamp – blinks when parity is checked or fill is transferred.
• Initiate push button – push this button when loading or zeroizing the KYK-13.
• Address select switch – seven-position rotary switch.
  • "Z" ALL – zeroizes all six storage registers when Mode Switch is set to "Z".
  • 1 through 6 – six storage registers for storing keys in KYK-13.