I'll try to clear things up. Arm restraints have two basic parts: the wide part that actually wraps around your arm, and an adjustable-length strap (typically 1" wide) that connects the wide part to your seat belt release mechanism. The straps need to be adjusted to the proper length to keep your arms inside the car.
On the old-style (now illegal) type, each strap was threaded through a set of dual D-rings and pulled tight to secure the adjustment length. However, it was discovered that if enough pressure was applied (e.g. in a high-G crash) the adjustment straps could slip through the dual D-rings, and your arms would then be free.
With a flat, "3-bar" adjuster (like that used to secure shoulder harnesses when wrapped around a roll bar, but narrower) when the adjustment straps are properly threaded, it's impossible for them to slip and free your arms.
But note that some arm restraints still use single D-rings on the ends of the wide part that goes around your arm. But that's OK. They're sewn in place and the adjustment straps just loop through them - they're not used to secure the adjustment straps to length. Some even employ single sewn-in rings on the ends of the straps that attach to the seat belt release mechanism, and they're OK, too.
Again, the illegal ones are those which utilize sets of two D-rings to secure the adjustment of the strap length.
Jeff in Boise
