None of the locks on these things are what anyone here would call secure, but this is probably as good as you can get. The TSA has to be able to open the bag for inspection. I don't believe Customs (at least in the US) will open your bag unless you are present but the TSA can for security reasons.
That being said, there are other things that you might want to consider. I travel extensively and have had many different bags. In my experience, the single biggest failure point on any roller bag has been the wheels. This bag has four wheels which make it easy to roll in any direction, but the casters are not recessed in the bag in any way and are more prone to getting knocked off or damaged. If anything happens to just one caster, the bag will be difficult if not impossible to roll easily. I have yet to see a bag with casters that can be replaced. Even some bags with only two wheels can be problematic since the construction of the wheels and bearings isn't great and on most bags the wheels can't be replaced if they go bad. I am speaking from personal experience here.
Also, the plastic hardshell bags are fairly durable, but once damaged, they are pretty much ruined since the shell is compromised. While it's not likely they will be damaged, it can and does happen.
A good compromise is a bag similar to this one:
http://www.stopoverstore.com/product/91 ... h-22-inch/I have a variant of this bag that has lasted for years. The wheels are recessed and you can replace the stock wheels with roller blade wheels which roll very smoothly. The zipper for the main compartment is much larger and heavier duty than those that you find on most bags and can be secured with a TSA lock. The downside to these is that they are heavier than other bags due to their metal frame construction. But they are repairable. You can send them back to the company for repairs, zipper replacement, etc. for free if they are in warranty and of course for a fee if they are out of warranty.
They're a little spendy as well, but worth every penny.
A cheaper alternative that has recessed wheels but isn't as secure is something like
this. Overall a nice bag but the zipper isn't as heavy duty as it is on the previous bag.
And if you recently won the lottery and want to spend a little more and still have a hard side bag, you could try this:
http://www.amazon.com/Halliburton-Zerol ... B002GTK3GEMade of aluminum with partially recessed wheels. Very durable.
Good luck!
-Mike
I have an amazing grasp of the obvious. Beyond that, not so much.