There is a bewildering array of head and neck restraint devices on the market. It can be a bit overwhelming to try and sort through them all. A great resource is Dave Gran's article on. GoAheadTaketheWheel.
I won't repeat what he covered regarding the politics and testing, but wanted to add my input after wearing this device for a few seasons.
This Pro Ultra version is the lightest model available, and subsequently the most expensive. The manufacturer claims it is less than 1 Lb., but that is sans padding and tethers. On my scale it comes in at 1 Lb 5 oz.
If it fits into your budget, it is well worth it. This device disappears when you put it on. The padding is attached to the carbon fiber collar by Velcro and can be easily rearranged to soften those pressure points.
The post attachment system comes standard. Some racers op for the quick release posts, but given the low profile of the back I don't find this necessary. I can slide in and out of the car easily without having to disconnect it from the helmet (even upside down, but that's another blog post) .
The belt guides are on the slim side, so if you're updating your belts, find some that are 2 inch at the shoulders. 3 inch belts tend to slide and cut into your neck.
While strapped in, lateral rotation of the head is more than adequate with the siding tethers. Not so with other devices I've worn.
The HANS design is tried and true, and this model is as good as it gets.