Radar

The Radar when equipped or in your inventory is an item that detects nearby enemies. It is one of the three parts necessary to make the R.E.K. 3000, with the others being the Lifeform Analyzer, and the Tally Counter. If you are within approximately 20 blocks of another player on your team who has a Radar, you can also see the enemies detected by their Radar.

It can spawn in underground wooden chests and wooden crates from Fishing.