The Firebird is an Innova Overstable staple that has been in production since 2000. It is the first disc I ever owned, thankfully in a 150g class. The Firebird is a very good headwind driver and it has a very predictable fade. It comes in a wide variety of plastic and a few different mold types. The firebird will have abbreviations on the bottom of the disc to help identify which mold it is. F stands for the original Firebird, FL stands for its less stable counterpart and FX stands for the most overstable mold of Firebird.
I use the Firebird for its reliability I know it will not turn over on me even in a gale force wind. That being said weight has a lot to do with its overstability (as it does with all discs). Lighter weights are more controllable for a new player but will still have a consistent fade. I can get my 150 to hyzer flip quite easily now that my form has gotten better and can turn it over if I throw it too hard. On the other hand my 175g CE Firebird is a beast that will never turn over unless it is put on a big Anhyzer angle. The firebird is a great FH Roller disc and I like it for downhill shots as well. The 150g is my get out of trouble disc and I can throw some sweet lines with it. The firebird is a great first oversatble driver because it is not too fast for a newer player to get a good flight out of.
The Firebird is produced today in DX, Champion and Star plastic. The DX will beat in the fastest and loose a bit of its stability over time. Pro Line will hold up longer and is a bit more overstable than dx. Champion is the most durable and most overstable. Star is in-between Pro and Champ. CFR Glow Firebirds are the most overstble but are only made for tournament fund raisers. KC 9x's are no were near as overstable as other firebirds and are oop and hard to find. I have a 9x and it is more like a teebird than a firebird. CE Firebirds are very overstable and are great for really windy days.
The firebird is a great disc because of the large variety of plastic it is available in and its dependable overstability. Not too fast but it defiantly takes some skill to throw with good results. If you want to go left (RHBH) this is a great disc to try.