From a highly experienced airline crewmember:

“I had been flying as an employee of one of the major airlines for decades, on long haul, staying in hotels all around the world and suddenly, out of the blue, something happened to me which left me quite literally aghast. Please permit me to tell my story.

Hotel room doors around the world are similar, mostly with electrically operated locks that are opened from the outside by a keycard. From the inside, they are simply opened by a large handle and, as an additional barrier to unwanted intrusion, there is usually a small switch which is the ‘deadlock’ lever. These are easily opened by anyone with a housekeeping master key.

To absolutely keep intruders out of your room when you are inside it, many hotels offer a further extra measure. The old-fashioned ‘chain sliding in a slot’ is looking a bit tired these days and probably on its way out. It is not particularly secure and easily forced. But increasingly common are two types of modern privacy locks you’ll have noticed if you are a regular hotel user. By privacy lock, I mean the mechanisms by which you can open the door a small amount to peek through a gap.

Making use of these privacy devices whenever you are in your room is a good idea. In this way, particularly at night, you can feel safe in the knowledge nobody can come into your room uninvited. Or so I thought.

I was staying in a modern well-appointed hotel in North America which had exactly the sort of doors I have described. In this case, the privacy lock was the sort which has a metal ‘right-angled’ flipper-bar mechanism - you’ll know what I mean if you have seen or used them before - once the door is closed, you flip it ninety degrees, into the path of the door, which can then no longer be opened. Crucially, there is still a ‘viewing gap’ made possible when the door is blocked by this type of lock.

I was woken by the sound of someone entering my room. Startled, I called out, and the person retreated, mumbling ‘housekeeping’, and closing the door again. The point is: I knew I had deadlocked the door handle AND flipped the ‘flipper-bar’ privacy lock. Both additional measures, designed to make me feel secure in my room, had been defeated by someone purportedly from housekeeping. This bothered me a great deal and I did some investigation into how this could be done. After years of being under the impression I was super-safe behind these extra locking mechanisms, it was quite shocking to find on the internet, videos of people demonstrating how easy it is to get past them.

There is something fundamentally important about the feeling of being totally safe from unwanted intruders, inside your hotel room, at night whilst sleeping or, say, when you are showering and you hear an unusual noise over the general sound of the shower itself. It is not a pleasant feeling. Especially if your eyes are tightly closed as you quickly try to wash away the shampoo.

So now I realised these privacy locks could be defeated in seconds, that assumption of total safety was lost forever, and this got me thinking about designing something which was easy to fit (and remove) in seconds, but which would restore that cosy secure feeling.

I designed two devices because there are two common types of privacy lock; the ‘flipper-bar right-angled blocker’ I already described and the older design which has a ‘metal ball sliding in a hinged swing-bar’. For each type, I realised I needed to design a different sort of product, and that is how I came up with stopBLOK and its sister-product stopBAR."

In both products, the key to their design is they prevent there being any ‘viewing gap’ between the door and the frame, by blocking the door from opening. It is the gap which is the vulnerability. By removing it, the only way to open the door is force it with so much force, the privacy lock is literally ripped from the wall’s screw fixings.