I just got an sa2015 helmet and am able to test this in the car with the harness on. So far, it doesn't seem to limit head motion at all? Schroth says its normal but its a little disconcerting to not be able to see how it works when sitting in the car. Is this normal for a HNR?

There is several inches of free hanging slack at the back belt loop. I am having a hard time seeing how this will restrain my head unless my neck stretches several inches.

Also, the review posted above has the anchors installed at the wrong orientation according to the instructions.

I noticed on hmsmotorsport.com over the weekend that the medium SHR Flex fits up to a 16.5" neck. They must have just updated the description because I don't remember seeing any specific sizing information anywhere else. It looks like Schroth added it to their website also. I'll be ordering a large one in a couple weeks.

If its like a Hans, you should just about take up all the slack when you touch your chin to your chest. One guy who's really knowledgeable about safety gear, including the Schroth Flex, is Eric at Team Driving Impressions (teamdi.com). May be worth giving him a call.

I ordered and received my Schroth SHR. However, one piece of the anchor assembly was missing and Schroth is sending a replacement. When I harnessed into my car the Schroth SHR felt more comfortable than my friend's Hans which put pressure on my collar bone area. His Hans large fit me well. I ordered the Medium schroth and it fits okay but is a little narrow for my neck. I'm probably at the crossover point for the medium and large sizing for the Schroth.

I'm hoping to put track miles on it this weekend if they get me the replacement part in time.

I did two days at buttonwillow this past weekend. This is my first experience with a Hans style device and overall I'm pleased with the purchase. I hardly noticed it while I was on the track and it was much more comfortable than my friend's Hans 2. I did get some light bruising on my collar bone from tightening the harness as much as I could. I might try to come up with a little padding for the arms for the next track day. But I'd take some light bruising over a broken neck if I ever had to put the device to the test.