Hi, I have the following classes: Client ClientCacheMedia ( contains Client, Media and some other parameters so it is the link between the media and the client) Media where client contains an IList. Now what i would like to do, is have a way to check if this ilist contains a certain media so : Client.ClientCacheMedia.Contains(MyMedia) is there any way to let the IList accept media as an object to match ? ( i can easily override the Equals Property on ClientCacheMedia to check if the media passed is the one that the ClientCacheMedia.Media contains, it's just the Ilist that will not accept any other object on the Contains Method.