Dynex is a normal SK75 spectra product. Dux is a version that has been pre-stretched under a proprietary heat process that aligns the fiber's and gives it the low creep characteristics. Dux comes in 7mm, 9mm, 11mm etc. Nothing smaller at this time. FWIW, we (layline.com) are a DUX retailer and distributor for Hampidjan

I'm in the process of replacing all of the standing rigging on my R33 and converting it to a canting rig using Dux 7mm.

I've already replaced the trap wires on my A-cat with 2mm Dynex (rated at 800kg). It's scary thin...