They are the same Ace locks as on the bike locks. Some people claim to have fixed it with a variable spring, but I've yet to see -anything- but an unsubstantiated post saying that. I would not buy a round key lock for any purpose these days. If I wanted high security, I'd buy a Medeco or Abloy cam (but a long screwdriver works as a "master key" on most RV hatches.)
I bought some "automotive grade" (i.e. double-sided locks with a metal shutter) locks. I prefer those over the round locks since they are more resistant to road grit intrusion, and the key is significantly thicker than the CH751 junk.