Firstly, the gauge is a gauge or something to measure how fast you are going in a car, not the name of the piercing. These are tunnels or cones or plugs. You don’t measure your ears, you stretch them. You don’t have to be of any age to buy cones. You can buy them on hot topic, bodyartforms.com, ebay, etsy, etc. You have to pierce your ears first and usually plug your ears back in, you have to be 14 with parental consent or 16-18 (depending on location) to get them without. You usually start with a 16g or 18g piercing and slowly stretch. It goes 18g, 16g, 14g, 12g, 10g, 8g, 6g, 4g, 2g, 0g, 00g, 7/16″, 1/2″, 9/16″, 5/8″, 3/4″, 7 /8″, 1″ and so on. 00g is usually the point of no return, meaning anything over that size has little or no chance of closing. Make sure NOT to skip sizes. Skipping sizes can spoil your ear, cause a rash, tear your skin, etc. It’s just a terrible idea. Wait 2-3 months before stretching a waist, otherwise it cannot be fully healed. If it hurts a lot, stop stretching and wait another month. Not skipping sizes and going slow also gives your ear a better chance of closing later if you decide to take them out. Otherwise, you need plastic surgery. It’s usually best to stretch after a hot shower so the fabrics are all loose and easier to stretch. You can also coat the cone and ear with an unscented lubricating lotion.