I saw this advertised on a sale site and got the system really rather cheap. I was exited to try it, because in the reviews it sounded so simple and easy to use. When it arrived in the mail, I couldn't wait to get started. I opened it up and then realized I needed to mold the trays to fit my teeth. Frustrating, but simple enough. I boiled the water and dunked the trays and molded them to fit my teeth. I read, and re-read the direction to make sure I didn't make any mistakes. After adding the gel, and getting the trays in my mouth, I didnt know what to do with myself. It was quite awkward to sit with the trays in my mouth. Then add in the uv light. My kids laughed, but I figured if it was going to work, they could laugh all they want. The taste in my mouth, not so good, but it was so bad that I had to spit it out. I drooled a little also, but again, if it whitened my stained teeth it would be worth it. After using the trays for 3 days I started to notice the difference. Its not a quick and easy system to use, but it is effective. Minimal Side Effects I didn't have any side effects while using this product.