R.E.K. 3000

Type	AccessoryCrafting material
Tooltip	Displays number of monsters, kill count, and rare creatures
Rarity
Sell	3 GC
Research	1 required

Desktop/Console/Mobile-Only Content: This information applies only to the Desktop, Console, and Mobile versions of Terraria.

The R.E.K. 3000 is a post-Skeletron informational accessory which provides information about the number of nearby enemies, the player's enemy kill count, and nearby rare creatures. It combines the functionalities of its ingredients, the Radar, Tally Counter, and Lifeform Analyzer.

Crafting

Result	Ingredients	Crafting station
R.E.K. 3000(Desktop, Console and Mobile versions)	Tally Counter(Desktop, Console and Mobile versions) Lifeform Analyzer(Desktop, Console and Mobile versions) Radar(Desktop, Console and Mobile versions)	Tinkerer's Workshop

Result	Ingredients	Crafting station
PDA(Desktop, Console and Mobile versions)	GPS(Desktop, Console, Old-gen console and Mobile versions) Fish Finder(Desktop, Console and Mobile versions) Goblin Tech(Desktop, Console and Mobile versions) R.E.K. 3000(Desktop, Console and Mobile versions)	Tinkerer's Workshop

Unlike most accessories, informational accessories such as the R.E.K. 3000 do not need to be equipped in an accessory slot. The R.E.K. 3000 may be carried in the player's inventory without loss of functionality, unless equipped to a social slot. Additionally, the info it provides will be shared with players of the same team in multiplayer that are within 50 tiles. Keep in mind modifiers will no longer apply to the player when not equipped.
In a drunk world, it is possible to get the R.E.K. 3000 before defeating Skeletron.

Selling the R.E.K. 3000 is more profitable than selling its separate parts (1 GC for the Tally Counter, 1 GC for the Lifeform Analyzer, and 50 SC for the Radar).

R.E.K. may stand for the words Rares, Enemies, and Kills, the three displayed functions of this item.
It is possible that the R.E.K. 3000 is a reference to the Garden of Eden Creation Kit, commonly abbreviated as "G.E.C.K.", and the Pip-Boy 3000 from the post-apocalyptic role-playing video games series Fallout.