Advanced Whitening Refill Gels x3Our Gel Refills contain key ingredients to ensure that there is no pain or sensitivity caused throughout the whitening process, while delivering results of up to 10 shades whiter teeth. (To be used with the Whites Teeth Whitening Kit). There are 7 treatments in each set so you need to divide the 3 syringes between 7 (just under half per treatment). If you fill the top part of the tray and put into mouth the the gel will spread into the bottom part