Have you ever been sleeping in a hotel room when all of a sudden the housekeeping staff walked in? It isn't a fun experience and can even be downright scary. You can prevent this (and curtail other threats) with a portable door lock like the Addalock. This ingenious device has garnered a lot of attention lately, and for good reason: It is simple, installs quickly and makes it much harder to get into your room. And right now it's on sale for just $18 (was $32) at Amazon.

Rishon Enterprises Inc.

Addalock the Original Portable Door Lock

$18$32Save $14

Whether you're in a hotel, a college dorm or at home, this portable lock can boost your door's security.

$18 at Amazon

Most people have lived or at least stayed overnight someplace where they didn't feel completely safe. When the hotel door looks like it's made of cardboard or the dorm room lock is just for show, the Addalock adds a bit of peace of mind to the equation. How's it work? Simple: It fits into the strike plate of the door and catches the door if someone attempts to open it.

It takes seconds to install, and it fits in most doors. There's a caveat there: if there isn't enough width between the door and the wall, it might not fit — but that points toward poor door installation more than anything else. It should fit most standard doors.

Best of all, this thing is tiny. It can fit into a purse or even some larger wallets. At just 5.8 inches long, 3.5 inches high, and less than an inch across (including the plastic section), the Addalock is ideal for keeping with you wherever you travel.

It's very well-liked, with more than 11,000 perfect ratings from Amazon customers. "I recently moved to a new apartment, where there is no entry code to get to your front door. So basically my front door is the outside door. But our doors can be opened by code, so Ring doorbells/cameras are not allowed. Which made me quite anxious as there’s only a door between me and the outside world," shared one shopper. "After I bought this, I could sleep so well at night. My boyfriend and I tested the potential for break-ins with this and it didn’t move. Of course we do have the longer screws in our door jamb, so the pressure goes directly to the studs. When I left the door unlocked this thing held its own. The utilization of angular pressure is what really holds it. And the strength of the metal."

Another customer supported this: "I wanted my wife to feel more secure in the home while I’m at work for the day, so I purchased this thinking, If it doesn’t work, I’ll just find another product, but I’ll risk the like $15 to see if it’s good. This thing actually works, and works far better than my expectations. I’m a large person (6’4", 400 lbs) and I tried to push the door in from the outside while my wife placed this inside. Not only could I not open the door, it didn’t even budge. I went inside and reattached it, then pulled on the doorknob as hard as I could. My whole door flexed, the lock didn’t move. I genuinely can’t believe someone designed something so effective and inexpensive that adds so much security. ... This thing rocks."

Right now, this lock is over 40% off, making it a great purchase for the frequent traveler.

Rishon Enterprises Inc.

Addalock the Original Portable Door Lock

$18$32Save $14

This top-rated door lock installs in seconds for added security, wherever you may go.

$18 at Amazon

The reviews quoted above reflect the most recent versions at the time of publication.

If you have Amazon Prime, you’ll get free shipping, of course. Not yet a member? No problem. You can sign up for your free 30-day trial here. (And by the way, those without Prime still get free shipping on orders of $25 or more.)

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