The Targeter is a function of the Tower Glove that allows you to change the destinations/length of items like teleporters and strings in your Condo.
How to Use
Right click on an item to select it; only items with destination points (strings, teleporters, launcher pads) can be selected with the Targeter.
After selecting a teleporter or launcher pad item, click to set its target point.
For string items, click once to select the starting point, and again for the ending point. In the tool settings (C) you can also have the Targeter skip the start point, and only set the end point.