I have been beta testing Kapture Group's latest sliding back for the Arca-Swiss RM3D for the last few weeks. It is a little more compact than the Arca-Swiss Rotaslide as well as less expensive. Both sliding backs are excellent in the field. The advantage of the Kapture Group one is that you can use a smaller 6x6 ground glass so that you can use any Hasselblad viewfinder (such as the Rmfx). With the larger 6x9 screen of the Rotaslide, your only choice is their huge and expensive binocular viewer, if you want to work with a non-reversed image. I can recommend this sliding back as an alternative if you need to keep things more compact and travel friendly.