This is the same stuff for a lot less cost than what I got years ago at my old dentist's office. I did not use the trays that came with it as I actually still have my trays from the dentist I had custom made to fit my teeth exactly. Getting the trays to conform properly to your teeth is the key to the gel working.
If you have the trays fitting properly, you actually don't need much gel. Just a drop in each tooth imprint only. And have a cotton ball ready to put under your tongue as otherwise you'll be spitting out excess foam for ten minutes straight (pro tip). I've done a few treatments so far and I can tell the difference. I also got several 5ml syringes of gel. With my well fitting trays that conform to my teeth, even one syringe would last a long time because I don't need much to get it to work and spread out. If you can't get your trays to conform you may need the extra gel but I have so much that I'll just save it in case I need to repeat in a few months (I drink a lot of dark sodas).
I'm very happy with this so far and plan on purchasing this again in the future if needed (and when I run out).