The Apex rear seat frame, is a great product, well built, really easy to assemble, however unfortunate the mounting points did not align with my NLR ERS4 Elite seat, I had to drill my own holes to attach it, which should be pretty universal. I am not giving it a 1 start because I did reach out to support before purchasing, and they did mention that even though the frame should be compatible with 99% of all chairs, I guess mine was the 1%, so I just want to advice everyone before buying.