Key bit (left)
From WikiRaider
Key Bit (left) is a part of a key in the level Red Alert! in Tomb Raider Chronicles.
To get the Key Bit, Lara must kill a cyborg by flooding a room where it is with water is and shooting the cyborg until it sparks. This electrocutes the cyborg, leaving the left Key Bit to the floor. Before hopping down to the room and picking up the Key Bit, it must be drained first.
The right Key Bit is combined with the right Key Bit to create a Helipad Access Key.