I use both silica and cotton with 32 gauge Kanthal using a 6/7 wrap. I usually end up with a coil between 1.9 and 2.2 Ohms. After you watch a few videos, this will become easier to understand. There are many choices in coiling, and I find it fun to experiment with different sizes, gauges and wraps. You must have a multimeter, and know how to use it, when recoiling. There are some decent 510 atomizer/cartomizer readers on the market, if you can find one. Get on everyone's mailing list because they sell out fast. As soon as you get the email, buy it, because they'll be gone 20 minutes later. Recoiling your first Protank is the start of a long and wonderful hobby with RBA's. I'm at the extreme start of it, but I've done maybe 50 Kanger coils, Genny and Oddy coils, and just got my Kayfun Monday and will be coiling it this week. It is surprisingly easy from an execution standpoint. It is surprisingly difficult to amass the knowledge and information to account for the many variables. I'm now studying airflow, invested in mini and micro drill bits and jeweler drills. Who knew that vaping would take me into the world of watchmaking and jewelry fabrication? I was a gunsmith for many years in a previous life, so the hands on work has not been hard. But the knowledge, well, that's something else, and endless hours of reading on the RBA and other forums has been required to get as far as I am. I would say I'm a solid 20% up to speed, and lovin' it! So, get started, get hooked, Power up and Vape On!