Expensive because it's job specific.If your the owner of a GM product with a 3.1 or a 3.4 engine this wrench will save you a ton of money by replacing the thermostat yourself.GM makes the bottom bolt of the stat cover almost impossible to remove without taking several parts off the D/S of the motor.This wrench will save you that time and money.One other tip:The bottom bolt hole is SLOTTED on the cover.Do not remove the bolt completely but just enough to tap the cover with a rubber mallet and slide it off.YouTube has some good information.The repair was still a son-of-a XXXXX, but I couldn't have done it without the wrench. Getting the thermostat bolt back in was the toughest. I had to use a screwdriver on one side and a finger on the other side of the bolt head to get it started then the wrench would clear the exhaust pipe to start turning. I chased the threads on the bolt and used some antisieze too. Must have been an angel on by shoulder because I was about to give up-last try and ten finally got the bolt to start. Was about to take the manifold off.3 stars due to quality issues. In the manufacturing process, the stamping of the box end portion of the wrench was about 3mm off; the head is small enough that this puts the wrench way out of spec.Fortunately, the wrench did the job it was made and bought for, despite the discrepancy in wall thickness. I am thankful that I shouldn't need it again soon.This specialty tool worked great! If anyone owns a GM vehicle with the very frisky 3.1L, they will want one of these tools if they do their own basic maintenance, which changing the engine thermostat is a common task. For whatever reason I have never seen this tool available at any auto parts or tool outlet store anywhere. I have purchased a few other specialty engine tools that were only available thru Amazon, so thank you Amazon for saving the day!Pros: I was able to get to that pesky bottom bolt on the thermostat housing easily.Cons: The material the wrench is made of is not sturdy and bent several times while trying to get off bolt. I was able to bend it back in place by standing on it. I ended up having to concoct another method to get the bolt loosened then I was able to use the wrench to finish up.It was an unusual configuration to me, but once I understood it, it did the job quite well.Tool did not work for intended purpose. Would have to b cut or bent in order to work waist of $It works perfectly