I only fitted them to a harness, because my friend bought them and he tried to fit it into the GenX 4+1 Harness and since they have that odd design they didn't fit. I noticed that ViewLoader Pods fit the best in a ViewLoader harness because they are designed for it. I don't know how that work with other packs but they did not fit this one. I realy don't like their shape anyway. I suggest getting different ones if possible.