If budget dictates that you stay in dingy hotels and cheap roadside motels during long travel, it's not unusual to be concerned for your safety. We suggest packing a gun. In case you'd rather not carry your own firearms, the Zelco Lock-Up Portable Door Lock might help you feel just a little more secure.
A carry-on accessory that you can temporarily fit into any door, it lets you add an extra barrier from inside without having to drill or permanently install anything on your doorway. According to the product page, the lock itself "cannot be dislodged or tampered" from the outside. It also reinforces the hold of the door, making breaking the barrier down all that much more difficult.
The Zelco Lock-Up measures 7.25 inches long, which should easily fit into among the pile of stuff in your luggage. It installs and releases in seconds, making it practically trouble-free to use. Both the casing and the lever are plastic, but the bar that lines up in the door frame (to add the extra hurdle to opening it) is all metal.
To install, all you need to do is insert the end of the steel bar into the door frame's strike plate, close the door, slide the casing against the door and push the lever to lock. With that, you've got additional protection that will keep the door shut even if an intruder picks your locks.
Amazon has the Zelco Lock-Up Portable Door Lock for $24.
Zelco Lock Up Door Lock
Sale Price: $62.32