If you're just using this in a hotel room, you probably don't care. But what if you're staying in someone's guest bedroom or with family or some other scenario where putting a lock on your door might be construed as rude or insulting?So you need the lock because you're planning on doing some incredibly embarrassing things behind that door, but you don't want anyone to know you have a lock because they'll think you're implicitly accusing them of being thieves. But if they find out the hard way, that's fine because they shouldn't have been barging into your room, so the necessity of the lock was just validated.In such scenarios, the big red arrowhead-looking lock isn't going to work because it is ridiculously loud no matter what you do. It's in the way that the metal slide is loose in its track and scrapes against the track and the metal plate behind it making an impressive racket. The solution is not to use that lock and instead use the much smaller, simpler, and quieter one that the kit includes.After having used the smaller lock daily for a week now, I don't really understand why the other was even developed. The only advantage that I can see it having is if there's a major disparity between the door surface and the surface of the molding. But it would have to be really severe. The small lock works fine with a standard 1/4" to 1/2" discrepancy. You would have to have 1" plus of difference before the small lock might not work. I don't believe I've ever seen a door like that, not in a residential home anyway. Maybe a bank vault. But then you're in a bank vault so you probably don't need this!Bought for $5.99 in Aug of 2022. Both locks work fine. The larger lock with the triangle piece is pretty easy to use. The smaller lock is a little on the small side for convenient use. They won't work everywhere though. Some doors are to close to the frame for the locks to fit between. Also some industrial doors (like hotels) can have locking mechanisms that leave no room for these portable locks to fit into. -- So, where they fit, they work well. Just don't expect them to work on every door you come across.Well, I bought this "lovely" house that is very old & well ya know how it goes when you get old you start to fall apart & have issues, yeah well that's my house. So it decided that all of the sudden it no longer wanted to allow the back door to lock, at all, dead bolt or the door lock, I tried pushing & pulling & lifting, it just wasn't having it so I needed a fast solution. After looking through tons of different options I thought this looked easy & it was supposed to super secure. Well, I got lined with door & my door was not happy about having a new contraction because as soon as I was about to get it closed the piece fell I tried to catch it & nearly slammed my fingers in the door, so that was my first experience with this. After finally getting it set up in the door it sagged like it was going to fall at any second, I did try to open the door & it did catch but it was not sturdy enough to seem like it could take a burglar trying to break his way in, but I wasn't about to break my door just to prove it. I ended up buying a different security lock that works much better & is so much easier.Love this handy device when I travel. Easy to install in the door of most hotels. Compact design. A little heavier than I expected but still easy enough to slip in mu suitcase and go. Would reccomend for any solo traveler or anyone looking for extra secuirty.I love this product. This is my second one that I orderedThe smaller lock was useless but the bigger one works well.I used it at an old hotel in San Fram last night and in the morning I was locked inside the room. I installed it as it stated but nothing could get the door open. I crawled out thru the fire escape. Two different hotel employees also tried and couldnt get it opened. They moves me to another room and will have their maintenance guy take a look at it in a few days. If he cant do anything about it, they will have to call a locksmith or TAKE DOWN THE DOOR! That is going to cost me bunch of money. I guess technically it did work. Just use at your own risk (especially in old hotels) as YOU MIGHT GET LOCKED INSIDE THE ROOM!Unable to have free USP p/u due to it does not fit MOST locks.