COG Tag 15 - Gears of War 3 Guide - IGN

After dropping the counterweight on the queen, proceed up the elevator.  At the top move to the right into the dark area. Opposite 3 arcade machines there

I've Got This! Achievement in Gears of War 3

Gears of War: Ultimate Edition COG Tag Guide - Hardcore Gamer

Gears of War 3: COG Tag and Collectible Locations for Act 4 [HD] - IGN

Act 3 Chapter 4 - Gears of War 3 Guide - IGN

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Gears of War Guide

Gears of War 4's Campaign Mixes Guns and Gore with Storytelling

Gears of War 3: COG Tag and Collectible Locations for Act 4 [HD] - IGN

Gears of War 4 collectibles guide - find every hidden collectible

James Dominic Fenix, Gears of War Wiki

Gears of War: Ultimate Edition COG tag collectibles guide: Page 4

Collectibles - Gears of War 3 Guide - IGN