Was just reading about a guy who had people enter his room at night in a hotel. Of course if you've a hacksaw or something you could also shorten the "wings" on the door side bit, to get same effect as a longer screw thread. I've a pile of rubber door wedges that are light, they'd probably do a similar job to be honest, I'll stick one in my bag next holiday.
The problem with this is 2 fold. First the strength is completely dependent on those tiny threads bearing the force and lets be honest cheap foreign metal isn't likely to hold up to even minor stress. The second problem is any gap shown like in your door for example when pushed open the force now no longer is parallel to the bolt where it's strongest but it is going to flex sideways. In your example bracing against a wood trim it will just dig into the soft wood and bend and give quite easy. The amount of "stopping power" this will provide is minimal maybe a small child at best. Any adult even a small female could shoulder through this device with ease. It's juts simple physics. You need surface area and better threads to make this work effectively. It's not worth $5 as it's a false sense of security that will let you down when you least expect it.
Yeah, that will buy you time, and will make the person after you lose the element of surprise, so… I’d say it’s a great invention. For its size and ease… I think it’s nice, but I’m already thinking of 15 days to improve it. One down side… A hollow door like a cheap inside door the wing is sharp and might just crush inside of it
Is someone after you? If you’re worried about home intruders, they’re going after the easiest targets. They’re not gonna try to break down a door that is jammed like this. They’re looking for people who are never home and have back windows that are easy to slide open. Stuff like this is really only for people who have someone after them who are determined to get to them. Or people who have a crazy landlord or ex who has a key to their place.
