MB Neon Jock Strap Yellow Medium from Male Basics Underwear. More information: SKU MBN04. Colors: Yellow, Red, Pink, Blue. Materials Polyester, Spandex. Brand Male Basics Underwear. Take a measurement tape and your posture should be nice and straight, without holding in or sticking out your stomach, Locate the bones on the right and left side of the abdomen. For Male Basics Underwear measure approximate 5 Inches under the belly button. Now locate the range between any of the values on the table and that would be your size. Men size medium 33 inches to 35 inches. To wash cold water, hang dry.