20% with PF Whitening Whitening Refill Kit (8 Syringes) Carbamide Peroxide. Made by Ultradent, in Melon Flavor. Tooth Whitening Refill Syringes - B-5401-4

Awesome gels, first time trying this particular type. The whitening effect is very visible even after the first wear, but most importantly there is no sensitivity even after using this gel 3 days in a row. Fantastic!

Works well and does not make my teeth sensitive.

Whitens really well - much better than strips. You do need to get trays; I had some custom made at the dentist and use the product about once every three weeks to maintain my desired level of whiteness.

I had professional teeth whitening done at my denti$t's office and the result was meh. I decided to try it at home using these syringes of bleach and my LED face mask for blue light. With the initial use, I had a better result than the one I had when the dentist bleached my teeth. My teeth are noticeably whiter. I went conservative and bought the 20% strength and left it on for 14 minutes with the blue light on medium---I'll use that as a baseline. No gum irritation & teeth aren't sensitive, so I will cautiously increase the times by one minute and the level of blue light. * Good tip is to use a generous amount of lip balm before you "Light up".

Squirt in your retainer. Wear it all night. Our dentist recommended this and it works perfect. Extremely white teeth

I ordered an 8pk of Opalescence from seller; product arrived timely and I am happy with product. For those using 15%- you may want to try the 20%- works just about the same- the 5% didn't seem to make much of a difference; however, I would like to comment on teeth sensitivity. If you have sensitive teeth, you may want to continue using what your dentist recommends.

Love this product! Recommended by my dentist. I leave them in all night a few times a month and never feel sensitivity pain like I do with other whiteners.

The process works with patience.