Anyone know anything about rear derailleurs?

[CrazyTeaPot]

Is this compatible with my bike, a mongoose deception?

http://www.amazon.com/Shimano-Tourney-TX55-Speed-Derailleur/dp/B003ZM9RDQ/ref=sr_1_5?s=sporting-goods&ie=UTF8&qid=1348808114&sr=1-5

[Stonerboy779]

Maybe, maybe not. Best thing to do is head into your local bike store talk to the staff and then after getting the recommendation go and buy the appropriate thing cheaper online.