I've been using the thinner road bike tire liner ones for years and rarely have had a flat (usually related to the odd sidewall piercing) so after getting a couple of punctures in my MTB tires decided to try these wider versions.
Just like the thinner road bike liners these work perfectly and have not had a flat since then. These are somewhat wider than the thinner road bike ones with a transparent strip on either side of the thicker inner (colored part).
There is a bit of a technique to getting a new liner in and to stay in exactly the correct place when putting the tire on - though if you're not too concerned I guess you can just throw it in between the tube and tire and be done with it.
I normally set the tire on one side on the floor position the liner just right and put a touch of air in the tube position the tube in the tire - the slight amount of air holding the liner in place; then carefully look under the tube with a flashlight to make sure the liner is exactly in the middle.
I then stand the tire up and start to put one edge of the tube into the wheel not fully around and just enough to hold everything in place then let out any air in the tube that might prevent the rim from going on properly and install the wheel rim normally.
As I said above - if you're not too concerned you don't have to go through the trouble and likely the liner will be in a relatively correct position anyway.
These liners whatever type you get - will not make your tires and tubes "bulletproof" but they will make them much more resistant than without so that only the most serious punctures are likely to occur. The kind of stuff only run-flat tires or Amish buggy wheels would be able to shrug off.;