[omasou]

You shouldn't really use belts w/o a proper installation, e.g. roll bar.

That said, in the past some people have bought or salvaged extra buckles and attached the belts to those and clipped them into the rear seat belt clips. Hope that makes sense.

EDIT: I was under the mistaken impression that the Schroth ASM technology was the between the thigh anti-submarine belt. Turns out after talking with them, the ASM "energy converter" is stitching in the one of the shoulder belts that on impact rips and allow the body to rotate like a normal street belt and would therefore allow your head to move out of the way of the roof, etc., if needed.

Wish they would explain this better on their web site b/c I would have been using their belts long ago.