Maintenance Jack

"The Maintenance Jack can be used to divert power inside an electrical junction."

- In-game description

The  is a tool used for unlocking doors that have security braces on them.

Summary
It also serves as the primary melee weapon in the game, and is the first weapon to be acquired. It can be used to stun and kill most enemies. When fighting a Working Joe, swinging the Jack will only work if the Joe is stunned prior to the swing or facing away from you, otherwise the Joe will grab Ripley's arm mid-swing and counterattack. The Jack has no effect on the creature. It can be used to smash a Facehugger to death if you swing before it leaps at you, but this costs a small amount of health.

Related Achievements

 * My Turn Now