R Parkerwrote a review of RockyMounts Lock Core Pack on March 20, 2013
Familiarity: I've used it once or twice and have initial impressions
I installed a set of these in 2 TieRods without too much trouble. I had seen some questions about if these would work with Thule racks (would be nice, I have a Thule hitch rack), and they look virtually identical to Thule lock cores. I called Rocky Mounts and turns out the locks are made by the same company, but one brand's lock cores are slightly shorter and are likely to get stuck in the rack. Supposedly this is due to the lock maker having a rule against supplying the same lock to two companies.
As noted by mccuden, it is probably not the best idea to use the key to pop out the plastic cover in the racks, I used the allen wrench included with the rack and it worked fine.