O2 sensor arrived well-packaged as usual. The sensor itself is also well-protected in the NGK box. The threads are pre-greased with anti-seize, which has a hard plastic cover over it to keep the anti-seize from getting all over everything until you're ready to install the sensor.I bought this for my 2004 Saturn ION Redline QuadCoupe, which isn't specifically listed in the models of cars that this fits. The Redline has a 2.0L supercharged 4-cylinder, while the other Saturns have a 2.2L non-supercharged. Some parts are specific for Redlines, and I wasn't sure if this would be one of those cases when I bought the sensor, but I figured I'd give it a shot. Glad I did - plugged into the factory wiring clip and threaded into the exhaust with no modifications. Also, this is the pre-cat sensor, which is the one that affects your fuel economy. The post-cat sensor is just a verification that the cat isn't clogged (I think).In changing the sensor, I found it easiest to drive the car up on to ramps to allow enough room to get at it from underneath. You'll be fighting the firewall and the brake reservoir and a hundred other things trying to get it only from the top. The sensor itself is located on the driver's side, upstream of the flange which connects the exhaust manifold to the down pipe (that has the cat as part of it). Remove the heat shield from the exhaust manifold, or you'll find it almost impossible to get a wrench around the sensor. The heat shield is held on by 1 bolt near that flange, and either 2 or 4 bolts near the engine - I can't remember exactly. Cut the old sensor wires close to the old sensor and use a box-end wrench. It's metric I think, but a 7/8" wrench worked for me. Do NOT cut the wire clip off the factory harness - you're boned if you do. JUST cut the wires AT THE SENSOR, so you'll be looking at the sensor threaded into the exhaust pipe with nubs of wires coming out of it.You don't need to tighten the new sensor crazy tight, just finger tight and then snug with a wrench. Hope this helps some first-timers out there.