Bachmann EZ Mate II couplers are just as good as Kadee's , in my opinion, and are cheaper.
Regardless of what you choose, buy a Kadee coupler height gauge - it will tell you what the correct height should be, as well as give you washers to help adjust the coupler height.
Regardless of what you choose, buy a Kadee coupler height gauge - it will tell you what the correct height should be, as well as give you washers to help adjust the coupler height.