The ACDelco Professional, premium aftermarket Ignition Lock Cylinder is the high quality replacement ideal for many vehicles on the road today. It is where you insert and turn the key to start the vehicle. When the correct key is inserted, the cylinder is unlocked and can be rotated. The ignition lock cylinder is connected to the ignition switch, and it also engages and disengages the steering column lock. This premium aftermarket replacement ignition lock cylinder is manufactured to meet your expectations for fit, form, and function.