I know the soft guards are bad because we have a tendency to chew on them while we sleep, plus, I've worn the soft ones for years and still have had to undergo 10 root canals, crowns and root surgery.
Dentists charge $600-800 for the 'custom hard ' ones. Ouch!
I bought a hard one off Amazon.
J&S Dental Lab Custom Teeth Night Guard - Upper
from J&S Dental
It's was over $100. They send you different size mouth trays and the putty to insert in the tray to make the impression. The kit comes with directions. Once you mail the formed tray back to the company, it takes 2-3 weeks to get the hard night guard. Once you get it, you still need to take it to your dentist to have it adjusted. I got mine and the way it hit my bottom teeth, it was putting pressure on my back teeth. Once he adjusted it, it's perfect now and I can feel the difference. Good luck.