Been using these for years, great value, no boil-to-fit, completely plug and play
My dentist recommended it, so I had him make me a custom dental guard for about $400.  The dog ate it (really - apparently pets like their masters' scents and it turns out these are very attractive).  So I had another one made for another ~$400.  I kept it out of reach of the dog but I eventually chewed it up, so it was time for another.  I love my dentist but this time I did some shopping and went through a couple of the kind you boil in hot water and/or otherwise mess around with to prepare for use and was completely dissatisfied.  Then I stumbled on this item on sale somewhere and THIS IS IT folks.
Rating: 5 stars