Review of TK-421 iPhone Case with Flip-Out Keyboard

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With the recent announcement of the Verizon iPhone 4 there will be more than a few Blackberry users making the switch over to the Cupertino created phone. One thing they may be missing with the iPhone 4 is the physical keyboard. Well there’s an app for that, actually there is a case for that. Today’s review item from Think Geek is a case with a built in wireless Bluetooth keyboard that provides a tactile interface for the Apple iPhone.

The TK-421 iPhone Case with Flip-Out Keyboard is designed to work with the iPhone 4; there is also a version of this case available for the iPhone 3GS. Due to the lack of Bluetooth support for the iPhone 3G there is no version for that model iPhone.

The TK-421 iPhone Case with Flip-Out Keyboard arrives in a red and black cardboard box with an image of the device housing an iPhone 4. The back of the package lists the features of the device. Inside the box we find the keyboard case, micro-USB cable and instruction sheet.

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The TK-421 iPhone Case is composed of black plastic with an open area in the front to store the iPhone 4 and the slide out keyboard behind.


The bottom of this case slides off for installing the iPhone 4. The case features openings on the sides, top and bottom for the various iPhone 4 controls and inputs.

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Resting behind the iPhone 4 case is a flip-out keyboard. A magnetic clasp keeps the keyboard in position. Found behind this keyboard is the power switch and micro-USB port for charging the keyboard.

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The keyboard comes in a QWERTY arrangement with 49 keys. Instead of using rubbery keys, Think Geek chose to use firm tactile ones like those found on most pull out smartphone keyboards. In addition to standard keyboard keys there are also multimedia controls.


Above the keyboard on the right hand side are two LEDs and the sync button. The two LEDs on the keyboard indicate the whether the battery is low with via the blue LED while a red LED lights up when charging.


The keyboard connects to the iPhone 4 wirelessly via Bluetooth 2.0. It runs off a built in rechargeable Li-ion battery, which takes 3-4 hours to charge.


TK-421 iPhone Case with Flip-Out Keyboard

Product Features
-Give your iPhone a real flip-out tactile keyboard
-Keyboard flips out for use, then flips back in when done
-Magnet based clasp keeps keyboard in position whether flipped in or out
-Increased typing accuracy and speed
-Precise hard clicky keys… not mushy rubber keys.
-Works with any app such as e-mail, web browsing, notes, and calendar
-Completely wireless Bluetooth connection does not use dock connector
-Keyboard powered by built in rechargeable battery, recharges via included USB cable
-Invented and designed here at ThinkGeek
-Models available to fit iPhone 3Gs and iPhone 4
–(Please note that the iPhone 3G will NOT work with this case. The OS does not support Bluetooth keyboards.)

Price: $39.99

Prior to first using the TK-421 iPhone Case it is recommended to fully charge the case. Once this is done, the iPhone 4 can be inserted into the case by sliding off the bottom section. Next place the iPhone into the case and replace this bottom section.

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The keyboard needs to be discovered via Bluetooth to work with the iPhone 4; this is done by powering on the keyboard via the switch in the back and then pressing the pairing button above the keyboard. Once this is accomplished, pair the keyboard using the iPhone Bluetooth settings screen. The iPhone 4 will provide a four digit pin code that must be entered on the keyboard to finish the pairing process.

Now the TK-421 is ready to be used with any app requiring keyboard input such as texting, e-mail, web browsing, notes, and calendar. Typing is relatively easy with the largish key-buttons. If you have used a Blackberry, Palm or other keyboard based smartphone then this type of input will be familiar to use.

One strange phenomenon I noticed using the keyboard as the input method was iOS would not recognize common shortcuts such as double spacing to create a period to end a sentence or auto capitalizing the next word after a period.

Besides the standard alphanumeric keys, red symbols are found along side most of the letter and number keys. The alternate keys normally found along the number section are represented by blue characters. The red symbols can be used by pressing the Fn button in conjunction with the red symbol or by pressing Fn and Enter to lock/unlock the red symbols as the main input. The blue characters are entered when pressing Shift with the corresponding blue symbol.

Media playback on the iPhone 4 can be controlled using the TK-421 with certain secondary buttons.

To conserve battery life the keyboard will shut itself off after a few minutes of inactivity. One drawback of the Bluetooth keyboard is the extra battery drain it exerts on the iPhone 4.

As a case the TK-421 protects the sides and back of the iPhone but leaves the front surface of the iPhone 4 totally exposed. All the buttons and inputs are accessible but slightly recessed. Certain headphone jack styles may not fit with the case in place.

The iPhone sits above the keyboard the case feels top heavy since the keyboard is much lighter. With the keyboard folded away the case feels bulky as the keypad doubles the dimension of a standard case.

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The TK-421 iPhone Case with Flip-Out Keyboard is a unique iPhone case as it provides a tactile keyboard for the popular Apple phone. It serves a dual function as a case and Bluetooth keyboard.

As a case it offers moderate protection but I would not recommend dropping it as it does not seem like it would survive more than a short fall.

The keyboard is compact with larger firmer keys than those found on most Blackberries. For those transitioning from the tactile keyboard smartphone world, the TK-421 iPhone Case with Flip-Out Keyboard is a great option for those who wish to retain physical typing feedback.


+Tactile feedback for typing
+Multimedia control
+Works via Bluetooth

-Bluetooth drains battery
-iPhone 4 top heavy


To learn more about our review policy please visit this page HERE.

  1 comment for “Review of TK-421 iPhone Case with Flip-Out Keyboard

  1. April 10, 2011 at 2:06 pm

    ThinkGeek’s description page says it will not work with the Verizon model of the iPhone 4 — have you found differently, and if ThinkGeek is right, do you know why this might be?

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