Inexpensive rubber door stops are a great tool for adding an additional layer of security when traveling. While many hotel rooms have a chain or sliding bar that can and should be engaged when in the room, these measures can be easily defeated if someone tries to force the door. More alarming some hotels do not have these features at all leaving the guest to rely on the room lock alone. In most hotels the majority of staff have access to a pass key giving them unrestricted access to all the rooms.
When traveling you can throw the doorstop in your bag. It weighs next to nothing and takes up almost no room. You might even consider taking two doorstops in your bag in case you get a room that also has a door to an adjoining room — then you can block both doors. Generally its advisable to request a room that doesn’t connect to an adjoining room but the realities of travel sometimes mean you may find yourself in that situation.
The effectiveness of the doorstop can vary based on the type of floor in the hotel room but generally it will impede someone from entering – at least from entering quickly and quietly.
There are commercial security doorstops on the market that incorporate an audible alarm into the doorstop. These are relatively inexpensive and can be a good option. One thing to note though is that because they incorporate batteries and wiring circuits they may draw attention if detected on x-ray machines at airports or other venues. Because they are an unusual shape and incorporate those components there is the possibility that you will need to remove them from your bag and explain what they are to security screeners in a foreign country who might be accustomed to seeing mobile phones or computers but not security doorstops.
This is not a major issue but something to consider, especially if you want to avoid scrutiny in foreign airports. The regular rubber doorstops will cause the intruder to either break-off their effort to enter your room, delay them from entering and force them to make noise announcing their presence.