10 of them.. It doesn't matter if you ruin a few. Easy.. microwave water in a 2 CUP pyrex.. Then dip and count.. I immediately ruined one got to melted and folded in on self. I had a good pair top / bottom and eventually will spend the time to cut, trim and mold a really great set.. but that was 3 months ago.. It didn't seem too important obviously.. 2 thumbs up.. look for instructions . You really need to focus on making the area GUM to 2/3 to tip a best tight fit.. Don't worry too tight.. It's impossible without some sort of jig,

Great quality product, easy to use and reasonable price. Can be used as bleach trays or night guard for teeth grinding and clenching while sleeping. The handle on it makes it easier to transfer from very hot water, (not boiling just extremely hot) to your mouth for molding it to your teeth. Super easy and if you don't get it right the first time, you can try again. Also there's extras for travel or loved ones. I love it!

These are just as good or better than any trays I've ever used through all the years. You need very hot water but not boiling water, so around 140 - 150 degrees is enough. You leave in for short periods of time then put in mouth to shape, repeat until form is correct.

I use the hot water from the tap and fill a drinking glass 3\4 full, add ONE piece to water. While that's in there I boil water in a kettle then top off the glass while stirring around with the tray. This will raise the already hot tray to the right temperature to be molded. By doing this 2 or 3 times at a lower temp you don't ruin the tray or scald your mouth.

When I put in my mouth I use my fingers and thumbs to press firmly against my teeth then close my mouth and vacuum the mold to my teeth.

It's easy-peezy.

These worked great for me, and I got a good set of trays the first try. I initially bought the Shine Whitening with Zero Peroxide that came with a set of trays. I had never tried whitening my teeth before, and the directions that came with the kit were not very good. This set looked pretty deformed. Once the plastic got stuck together, there was no getting it apart.

I ordered this set to give it another shot, and got a good set of trays on the first try. I filled a glass measuring cup with water, and put it into the microwave for about 1 1/2 minutes until it was boiling. Then I held the first tray into the boiling water for 6-8 seconds until it was just starting to soften. I let the excess water run off of it and put into my mouth on the bottom teeth being careful that it went over the teeth. Then I sucked in my cheeks with my mouth closed. This pulled the tray up to my teeth. Then I used my fingers to make sure that the tray was formed to my teeth, took it out of my mouth, and rinsed it with cold water.

I did the same thing with the second tray without re-boiling the water, and put it on my upper teeth following the same procedure. Again, I had a perfect tray. I think the problems happen when the trays are left too long in the hot water. This will make them too soft and limp. If you try to shake off the excess water, the soft plastic will stick together and you will never get it apart - especially if you got it too soft.

In summary, to get perfect trays the first time, do one at a time, don't leave them in the hot water too long, don't shake off excess water (let it run off), and suck in your cheeks to pull the forms close to your teeth.

They work perfectly, if you do it right. These trays are made from a very soft, pliable material. When dipped in water that is at a rolling or near rolling boil the tray will almost immediately shrivel, rendering it useless. I followed the instructions of several previous reviewers who essentially said: Fill a glass quart measuring cup with water and put it in the microwave for about two or three minutes, depending on the strength of your microwave - *remember - hot, not boiling water.* Dip one tray into the hot water for about six seconds (don't over do it) then put it in your mouth and kind of vacuum seal it around your teeth by sucking the air from between the tray and your teeth. If the tray does not get quite as tight as you like, dip it in the hot water again, for a couple more seconds, and repeat. This works for the upper and lower trays. Honestly, my first attempt at fitting the trays was not great - not terrible either - but not great so I had to give it a second try. The second set was perfect. When I helped my husband with his set, it was perfect the first time. I was very happy to have five pairs of trays - an extra for practice. I have been using these with, Watts Power Deep Stain 36% Whitening Gel, followed by, VitaBrites Remineralization Gel and am absolutely thrilled with the results - for myself and my husband. For nice, white, healthy looking teeth, the price is outstanding!