It is no secret, especially among gamers, that a wired connection beats a wireless one any day of the week and twice on Sunday! This includes online gaming and wireless audio, which are naturally prone to speed, latency, and interference issues.
Just the last year alone, wireless technology seems like going at a galloping pace in its quest to take over everything, including the gaming world. Wireless controllers have actually been around much longer though, going as far back as the 1980s where the Atari Game Mate 2 came into existence, being the first wired-free controller. 

Technology is a funny old game though, the more new tech seems to push forward the more push-back it seems to get. This appears to be the case with wired technology which doesn't seem to be going down without a fight. Case in point, it's the GameSir X2 - a wired mobile game controller that has the potential of shaking wireless controllers in their boots. There is also an X2 Bluetooth controller version, just being released.
The GameSir X2 controller has a telescoping mechanism designed to cradle the phone by clamping both ends via a spring loaded plastic slider built-in to the frame of the GameSir X2 that allows the right side of the controller to extend outward and recoil. The GameSir X2 controller has a flexible USB-C connector, which can freely move up and down up to an angle of 50 degrees. 

The flexible USB-C connector not only makes inserting the phone easier, it also minimizes strain on the connector. The USB-C connector has a good length to fit a phone with a protective case although, depending on the thickness of the phone case, you may or may not have to remove the phone case to make a good connection.
Slotting the phone securely into the GameSir X2 is easily done in two steps by first sliding and connecting the phone and then, pulling the spring loaded right side outwards until the phone slots securely into place. The entire controller is made of hard plastic with an ergonomic backside shaped similarly to the hand grip of a console game controller. The palm grip areas are rubberized with a dotted textured finish. GameSir brand etching can be seen on the front and back.
Without extending it, the dimensions of the GameSir X2 are 175mm long, 85mm wide and 35mm high, including the height of the joysticks. The cradle area measures 95mm long and 80mm wide and it's made of grippy rubber with a maze-like honeycomb surface finish. The sides of the cradle are also protected with thick jagged rubber, which prevents both sides of the phone from slipping off the cradle enclosure. The clamping force is medium/high. Total weight of the GameSir X2 is 167 grams.
The GameSir X2 can physically extend up to 240mm long but, it can only accommodate USB-C phones up to 167mm long; hence any USB Type C smartphone that is 6.5 inches long or shorter. Aside from the USB-C port hardware requirement, there is also a software requirement that requires the Android USB-C phone to be running Android 9.0 or a newer version of Android.
If your phone isn't running Android 9.0 or above, the GameSir X2 controls won't work properly. The phone also has to support OTG function for GameSir X2 to be able to communicate with the phone. Not all Android phones support OTG so, you really want to check first, which you can easily do by using a mobile app such as USB OTG Checker. If your phone does support it, you many need to turn it on from the phone settings. If you have a Xiaomi, Google, Huawei or Samsung phone, OTG will be turned on by default.
The GameSir X2 face buttons and bumper buttons are made of plastic and have carved symbols on them. The R1 and L1 bumper buttons are smaller with a flat surface, while the R2 and L2 bumper buttons, which are digital, are larger with a slight concave shape that hugs the finger. All bumper buttons make the same loud clicky noise when pressed. As far as buttons, there are four face buttons and a split d-pad with four separate buttons. All buttons, including the d-pad buttons have similar responsiveness and make a quiet sound when pressed.
There are two rubberized analog joysticks, which are accurate with good resistance. The face buttons have an ABXY button layout; hence buttons A and B have inverted placement, which maybe confusing for someone who is used to playing Xbox games with a BAYX button layout. The ABXY layout was actually started by Sega in the Genesis controller and means the A button is located at 3 o'clock rather than 6 o'clock, while the B button is located at 6 o'clock rather than 3 o'clock.
There are no analog triggers on the GameSir X2, which is actually a good thing because binary buttons (i.e. bumpers) seem to work much better for Iron Sights ADS (Aiming down sights) than gradual buttons (i.e. triggers) at increasing accuracy and the ability to control recoil in First Person Shooter (FPS) games.
Because the GameSir X2 has four top bumper/shoulder buttons, you can have your index and middle fingers on all four bumpers, which is something you can't do with controllers that have triggers and bumpers. Not only is more convenient having bumper/shoulder buttons, it is also better for your gaming performance since a lot of games such as Battlefield: Bad Company and Battlefield 4 require being able to quickly spot and shoot, which is easier done with both sets of shoulder buttons.

When you're done gaming, you can use the GameSir X2 controller as a phone stand charger to charge the phone and/or watch content. There is no kickstand though, so you will have to rest the GameSir X2 controller against another object (i.e. keyboard) to keep it upright. If the GameSir X2 controller had a built-in kickstand, it would definitely make it an even more useful device since extra functionality is always welcome.
GameSir X2 does require power to function, which it takes from the phone but, it draws hardly any current; hence power consumption is not an issue. GameSir X2 is plug and play so, you literary connect the phone, run the app and you're good to go. GameSir X2 works with games that support gamepads, including the GameSir Egg NS emulator, which is a closed source paid emulator only compatible with the GameSir X2 controller. While there are a lot of Egg NS games that are compatible, not all games are playable.
While the phone sits inside the GameSir X2 controller, you can charge it via the built-in USB C pass through port, which allows charging to pass through to the phone. The USB-C port is just for charging; hence you cannot use it for anything else like connecting a pair of wired headphones. Because of the design constrain, you won't be able to use the headphone jack (even if the phone has one) because it gets blocked.
The GameSir X2 is exclusively a mobile controller for Android phones and resembles the Nintendo Switch, although the X2 is a lot more compact so, holding it for long times may not be as comfortable for someone with large hands. Smaller hands definitely feel more comfortable to grab on to the X2 controller. Being wired, it is powered by your phone's battery so, you don't have to worry about the controller running out of battery in the middle of a game. The GameSir X2 controller doesn't have any wires so, it does have that in common with wireless controllers plus, it is more reliable too without delay issues.
A few other things worth pointing out about the GameSir X2 are no built-in speakers, no proper d-pad, no XInput or memory card slot, which would make the GameSir X2 controller more awesome, especially if it came pre-loaded with old school games. The GameSir X2 controller comes with a sticker but no other accessories like a charging cable since it's powered by your phone. You can buy the GameSir X2 telescopic game controller from amazon. Check out the review of the X2 Pro telescopic controller