We suggest 18g-20g and 5/16" flat backs or butterfly backs for standard earlobe jewelry. If you decide to go with threadless earlobe jewelry, keep in mind the tops can range from 2mm-6mm. If you prefer a hoop the most common size is 16-20g 5/16" or 3/8" Still unsure of what you need? Don't be shy, shoot us an email god@metalillnessjewelry.com.