I spoke with my contact at Thule and she said lock cylinders are interchangeable between the Thule Snug Tite Hitch Lock, # THSTL2, and the Thule Aero Roof Rack Support Feet TH400XT. She suggested first ordering the Thule Snug Tite Hitch Lock and Anti-Rattle Device, then you can get the number off the cylinder and call our customer service and we will be able to send you matching lock cylinders and keys for your Thule Aero Roof Rack Support Feet. view full answer...