I recently got back into the hobby but am still a newbe and don't know very much. All my old locos and rolling stock have standard Rapido couplers. Last week I went to the Reading Pa. train show and bought some coal cars that matched some of my old road names. Not being very observent, I didn't notice until I got home that they had knuckle couplers. In reading through the forum I came to the conclusion that Micro Trains makes a good product so I bought some and installed them on my old coal cars so they would work with the new ones. Worked like a charm. I have since noticed that most new locos & rolling stock now come with knuckle couplers. If you guys can help me out with these Q's I would greatly appreciate it: 1. There are several manufactures of knuckle couplers. Are they all compatable? 2. When you by a new car how can you tell which manufactures coupler is on it or doesn't it matter? 3. MTS makes 10 differnt types, whats the diffrence?