Earlier, we looked at a security bar by Master Lock. While we are focusing on this bar again, the idea will be the same for any of the similar adjustable bars we looked at.
Using this bar is incredibly simple, as all you need to do is remove the part that would attach to a regular door handle, adjust the length and then insert it into the door. The product page features a handy video that shows you how easy it is to insert this and similar bars.