It is a light olive-green device with a light tan button, a red dial, and a light gray antennae. It is used to track sea sponges within a mile radius, and uses a realistic image of them on the device.
Role in episode
Sandy invents this tracker after SpongeBob goes missing and the gang tries to find him. Squidward, not wanting SpongeBob to come back, purposely destroys the device with a hammer. He then claims that he dropped it, but nobody buys his blatant lie.
This is Sandy's second invention destroyed in the episode, the first being her robot, which was destroyed by SpongeBob.