I put my first Accurail hopper kit together last night, actually it was a kit of three hoppers. Instruction # 4 advised me to install my choice of couplers that were supplied in the boxes. Apparently, there are three different types of couplers. I couldn't decide which one so I just winged it and said, "eany,meany,mindie,moe." Two style couplers had the plastic spring and the other did not so I first choose the one with the plastic spring,however it doesn't seem to be a very good coupler.Then I experimented and assembled another coupler using two plastic pieces with springs. It looked prototype but what do I know. Then there is a third coupler that I didn't bother to use. Sorry I can't send pics so you could all have a good laugh but I am not that computer literate yet. These couplers mate with Bachmann couplers on an old train set. Perhaps ya'll can shed some light on this subject as the picture in the instructions leaves something to be desired when you don't know what you are looking at. By the way, is there a thread on Kadee couplers that I could read?