The slide of a semi-automatic pistol (also called a pistol slide) is the top assembly of the weapon. It usually comprises the firing pin or striker, the extractor, and a housing. It serves as the bolt as well. When the pistol is fired, the recoil pushes the slide back across the top of the weapon. As the slide moves back, the extractor pulls the now-empty cartridge case out of the chamber and ejects it. In single action pistols, the recoiling slide will also cock the hammer back. When the slide reaches the rearward point of travel, a spring pushed it forward again. As it moves forward, it will push a new cartridge, raised into position by the magazine follower (if one is available) into the chamber and leave the pistol ready to fire again. If the magazine is empty, the slide will lock back at its rearmost point, leaving the chamber empty. At this point, a new magazine may be inserted, and since the slide remains locked back, the pistol may be brought to battery by simply pressing the slide release lever which will allow the slide to move forward and load a new round.