Detonation Key
From WikiRaider
The Detonation Key is a Key Item in the level Bartoli's Hideout in Tomb Raider II.
Lara use it on a detonator to explode the prison that leeds to the Opera House.
Their is also a Detonation Key in the Nevada Desert in Tomb Raider III. Lara use it to explode the ceiling that leads to the High Security Compound.