One of the best coil starter kits. At first glance these coils are very well built and high quality - I've attached a photo of the alien coil. On the medium/large size in diameter and in general, and all of them are flat, except the 'spaced clapton'. Also, they seem to be made of stainless steel, but feel free to correct me. I've really been enjoying them. Good flavor, and the coils are actually what they say they are, unlike some other cheap coils. For instance, the clapton coil is a REAL clapton coil. Also, it's really awesome that this set comes with 4 aliens! I've found that the flavor I get at first is amazing, and definitely above average, but the flavor drastically diminishes throughout use. They could definitely last longer, but I find the flavor to be significantly weaker after 2 or 3 days of use. These coils have a hard time soaking up the juice in my cotton, as someone who switches flavors often I find it quite annoying. With other coils, I can vape until the cotton is dry, but these leave the cotton soaked even after I've been vaping a while and the flavor has diminished. These were definitely worth a try, and are a great value.