As several mentioned below, this is an incredibly easy-to-install system. NO INSTALLATION TECHNICIAN IS REQUIRED. I asked one for information, and he asked me nearly double the money (purchase and installation) than what I simply paid for the purchase and installation myself. Extremely user-friendly with the mobile app and commendable. Other reviews mentioned some fake alarms that may arise from the installation, which I did not encounter. I simply followed what the instructions say during installation and some YouTube videos for confirmation. The only negative thing I can say (but it's for the future) is that the hub sold in the packages as a starter kit has a 2G SIM connection, which does not support the radar with the camera. Just be aware of this before your purchase. Of course, for now, the starter kit has the most competitive price, and buying the newer hub costs as much as the entire kit, making it unfeasible. Also, some scenarios mentioned in the reviews that you can create, which I have not seen and do not know if they pertain to newer equipment. Logically, there is no second scenario other than the alarm going off when a sensor gives the signal. It may relate to the use with a SIM card and whom to notify. Overall, this is a very good system that is worth this small investment.

Detailed Review:

The product is excellent. I believe it is rightfully called the "Apple" and "Ferrari" of alarms.

First of all, let's start with the design: Incredibly elegant design, and very good quality materials (although plastic). Both the black and white colors are very beautiful and blend well with home decor.

Moving on: Installation is a breeze for anyone with basic knowledge of mobile phones. I emphasize the most important point: NO NEED FOR A TECHNICIAN. One can install it by themselves, either by screwing in the sensors or simply using 3M adhesive (each sensor in the package has it, which is very durable) for those who do not want to drill walls/doors/aluminum.

Incredible functionality in terms of settings, you can truly customize the alarm to fit your home and preferences. Through the app, you can literally control EVERYTHING, easily and quickly. The app is incredibly functional and you can see everything from your mobile phone. You can arm and disarm the alarm from anywhere. To understand, the system is so advanced that when I tried to arm/disarm it from another city, it sent my wife a notification that the alarm was armed and disarmed from that specific location I was in, with pinpoint accuracy and a mark on the map (Ok, this is not very good, someone will say :p)

Personally, I spent 500 euros to get the starter kit and some extra sensors, and then every month I would get something "extra" to complete the system. And here is one of the most important features of this alarm, in my opinion: You can "build" it gradually. The philosophy is that you can gradually add sensors to the system, at a later time. We live in times when 600 and 700 euros are not abundant for anyone. You can simply start with the starter kit and every month get, for example, a 60 euro sensor and gradually "build" it. From nothing, it is something.

If there is something "negative" (which I do not consider so negative) is that Ajax has not yet launched cameras. Of course, you can "connect" any IP camera to the system, however if it is not Hickvision or Dahua, you will have to "integrate" it with the RTSP protocol, something that those who are not fully familiar with technology will find difficult to do.

Recap: For those looking for a reliable, wireless alarm, Ajax is the perfect solution. With closed eyes!

We are really talking about the Ferrari of alarms. The simple kit with the trap, motion detector, remote control, and hub is not enough as you also need to buy the siren (about 50 euros). Very easy to install and everything is wireless. This specific hub allows you to play with many automations.
For the purchase, I relied on comments from Greece and abroad from users who have had it for 2+ years without any false alarms (the most important thing). In addition to this purchase, I also added the siren and a fixed ezviz camera without PTZ but with motion detection, which is compatible with the hub!! (50 euros for the camera)
The potential buyer should keep in mind that each trap costs 30+ euros and each detector costs about 50 euros (it's worth it) and that they will need the support of the store they purchase it from for the initial setup, only over the phone, just to finish it in 30 minutes. Otherwise, with the tutorial and no help, with very basic mobile knowledge, it will take about two hours

Owner of the ajax hub 2 plus. Bought from Romania or Ukraine (half the price compared to Greece). Reliable and easy to use. It takes a little bit of time at the beginning to set it up according to your preferences (although it comes pre-configured), but everyone's needs differ from house to house.

For example, if you have multiple windows and entrances, instead of buying a sensor for each opening, you can use a motion sensor. However, when you sleep, you will need to activate it completely (not just within the house). This means you need to set it to activate within 5 to 10 seconds from the moment it detects motion, so you have enough time to deactivate it. Overall, it works very well and without false alarms.

The plus 2 version that I have supports 2 SIM cards (I haven't activated it yet). I haven't found a card from any other company that requires a quarterly renewal fee of 10 euros. I got one that doesn't expire, but it doesn't work because when you make a call, it disconnects and the center calls you back and connects you to the number you dialed.

I also used the rex (repeater) because the peripherals are connected to the hub, not the WiFi network (which is more secure). The anti-jam feature is very important, although I haven't tested it yet... That's it

After 8 months of use, I have to say the following:
1. The system is truly reliable and has many functions and capabilities.
2. Through the installed application on the phone, you can customize almost everything. You can enable or disable each peripheral, change its sensitivity, whether it will give a command to the siren, and how it will work exactly.
3. If properly configured, there is no chance of false alarms.
4. Some attention is needed for the external motion sensors. If they are completely exposed, then their cover will be necessary because in case of heavy rain or snowfall, it will notify you that it is covered, resulting in the siren sounding even if the alarm is not armed. Of course, there is a suitable setting to avoid this.
In summary, after 8 months of operation and because the system I have is equipped with several peripherals (indoor and outdoor radars, traps for windows and shutters, keypad and external sirens, etc.), it is a very reliable system that will not betray you. Since the communication with the alarm is done via the internet or alternatively, in case of emergency, via GSM, the communication with it will never be lost.
Finally, with the long battery life, I can say that you can sleep peacefully and not worry about power outages.
A truly wireless alarm (you won't see any cables anywhere).

There is no system... anything in front of it is simply like comparing roller skates to air-filled ones.

It has countless peripherals that you can easily connect (from opening sensors to flood sensors and smoke detectors), the only thing someone needs to know is that the magnet for the door sensors should be placed on the top right of the sensor (the one with the light) and the sensor is the one that should be placed on the moving part if we are talking about the plus version with vibration (otherwise it doesn't matter).
Forget all the ancient systems with codes and troublesome unstable settings, forget about assumptions of accidentally triggering... you just don't care in general.

It has Geofence: you can set it up so that when you leave the house (via the mobile app, where everything happens) it notifies you to arm it if you forgot or disarm it when you're approaching... it has endless features. It doesn't use the same communication protocol as common wireless systems that may or may not work, the manufacturer guarantees a minimum range of 1500 meters... In my 90-square-meter house with multiple outdoor areas, I didn't encounter the slightest problem.

It's worth every penny, I highly recommend it without hesitation.

After much research and waiting for years (I constantly postponed it) waiting for the competitors to drop their prices or improve their products....I ended up here. It may seem expensive, but it is the only one that really works as it should. After calibration, I never had a false alarm. It is very user-friendly and you can change settings from your mobile phone at any time. You can perform tests and coverage zone experiments with your mobile phone. On their website, they have features that you can upvote, what more do you want the developers to add to the software?! Something I have never seen in other products! If it wasn't wireless, it would have a certification higher than grade 3 (like the ones they use in banks). My friends bought smart Chinese alarms and regret not spending extra money to get the Ajax. They definitely don't feel confident that it will work when it needs to, plus they have lost a bunch of features that you can only understand by seeing the software.
+ The software is well-designed without bugs.
+ Incredible settings and scenarios that you can create, which other alarms can't even imagine.
+ It is upgradable and has amazing customer support (they respond to your emails within a few hours).
+ It connects to a signal reception company.

-The batteries in the Radr, sirens, etc. don't last for the 4 years that the company claims, but about 2.5 years.
-There are peripherals from AJAX with different firmware and hardware that can do more things, but they are sold as the same type.
For example, there is an AVAX Stet siren version with software that supports the Chime function, and others that don't. You don't know what they will give you! Unacceptable.
-The alarm supports 2G - 3G backup. As 5G has arrived in Greece and the frequencies of 3G have been abolished, it is left without backup! (With 2G speeds, it is impossible to handle it). They still sell it! Go straight to the next generation of AJAX if you want mobile backup.
-The software application takes a long time to activate when switching from data to Wi-Fi on the mobile phone, which can cause false alarms when entering the house and connecting to your home's Wi-Fi.