We suggest 16g 5/16" or 16g 3/8" depending on your desired fit. If you decide to go with a flat back stud we have three different ball end sizes ranging from 2mm-4mm. For those that prefer a hoop, 5/16” will create a snug, fitted look. Keep in mind that lengths may vary per person size up or down to find your desired fit. If you are unsure what you need visit us in the shop at any Platinum Ink location for any sizing needs or shoot us an email at god@metalillness.com.