This model of keyfob is used on so many Rover vehicles including various Land Rovers including Discovery, Defender and Freelander model. Essentially if your key looks like this then it's the right one.....simple!
The rubber buttons tend to break down and go disgusting and the plastic itself obviously becomes tired and old over time.
Fitting is extremely simple, open the fob (good time to change the battery) and move the plip chip from the old one to the new one and clip it together.
In terms of quality, these are the best ones we have found which is why we sell them. They are Lucas branded and have a lock symbol on the lock button unlike the cheap versions with blank buttons.
We use these ourselves and have never had issues or negative comments.