When teamed up with a Beacon, the target teleporter instantly transports you from its location to the paired beacon. You can set them up for short or long distances, but how far apart is dependent on your Engingeering skill. The Target Teleporter will determine the start point of the teleportation.
How to Obtain
The target teleporter can be crafted or acquired from chests as loot. If it drops as loot, it will always be paired up with a Beacon.
How to Use
To set up a Target Teleporter, you must also have a Beacon. First decide the location you want to start from, and place the Target Teleporter on that spot. Decide where you want the player to transport to, and place the Beacon in that location. You will know that it worked if the Target Teleporter has a blue fire coming from the base.
Your Engineering skill determines how far you can teleport; multiply your Engineering skill by 10 to calculate the maximum distance you can place the two apart. For example, if your Engineering is 6: 6 x 10 = 60 blocks. If your Engineering skill is maxed out at 15: 15 x 10 = 150 blocks.
Just like how you set up Beacons and Target Teleporters like switches and doors, you can use a special trick to link multiple Target Teleporters to a single Beacon. To accomplish this, you must first place a Target Teleporter and a Beacon in their respective desired locations as described above. Next, mine the Beacon (DO NOT TOUCH THE TELEPORTER). The blue fire on the Target Teleporter will go out, but just be patient. Now, place a second Target Teleporter in the second desired location and then place the Beacon back in the exact same spot you did initially. If you did everything correctly, you should have 2 Target Teleporters linked to a single Beacon (destination).