Thongs are great for avoiding panty lines, but it's very easy to get "thong butt" if you lean over or favor low-low-low rise pants. The Y-string solves the problem by using straps that fit over the hips and join at the bottom, where they are tightened to fit with an adjustable band. No straps, no panty lines.
It's not available yet, just one of the ideas in development at IOL.