Werner Yes no doubt the E3 is not a substitute for the C7. An individual contacted me and asked if I might be interested in trading my C7 for another of his Medx pieces. I considered it because I was interested in using more single joint machines I currently also have B1, B7 C1, G1, F2, F3 in single joint. The compound machines I have are B6, C3, D6, E1, J2 andJ4 I train about 25 clients privately and for the past few years have been training all almost exclusively with compound movements. My philosophy and approach are changing (thanks to the influence of your writings) and I have been putting more emphasis on lumbar and cervical spine strengthening and more single joint movements. So when the opportunity presented itself to maybe acquire a single joint machine I considered it. My concern as you have answered is that the C7 out of all the pieces I have would be the only one to engage the rhomboid function. Would the C5 do the same? Dennis