20 inch,24 inch,28 inch, can be stored one into another.
The carry-on size dimensions will meet most airline approved.
HOW TO RESET THE TSA COMBINATION LOCK
1. The lock is set to 0-0-0 at the factory.
2. Make sure the dials are rotated at 0-0-0 or any other code you've set before resetting it.
3. Use a pen or something pointed to press the reset hole adjacent to the dials.
4. Enter your new code by rotating the dials
5. Push the key button once and your code is now set.
6. Scramble the dials and test your new code to be sure the correct one is set.