The Glow Stick is a gear item appearing in Rise of the Tomb Raider. It is used to illuminate dark places and replaces the Torch used in Tomb Raider (2013) which had to be lit up manually and could be used to solve certain Puzzles.
In Syria Lara Lara carries a blue Glow Stick, while in Siberia she has an orange-red one. Whenever she enters some cave or other dark area in the game, Lara automatically gets out a new Glow Stick and puts it on her belt. Unlike the torch from the prequel the Glow Stick serves no other purpose than illuminating the game and can not be used to solve puzzles. It is also not listed in the inventory.