My HHV helment came with these rails and I also purchased this replacement set in another color before doing my reasearch.
They are solid and made of a durable quality! However, none of my accessories are mloc compatible thus I'll need to purchase more items through HHV and that drives up hidden costs. My other issue is that mud, gravel and dirt get trapped in the holes. Rinsing it off did not work. I had to completely disassemble my helment in the field to clean them and that's not fun. I really prefer a standard rail system.
I purchased these thinking I would put them on my existing helmet, unfortunately it doesn't state anywhere on the site that these will only fit HHV helmets. Now I'm stuck with them. They seem well made.