Most underwear fabrics consist of a combination of nylon, elastane, polyester cotton, and modal. "The fabric fibres themselves aren't always more or less durable per se — it's the specific fabric combinations and quality and the where and how the fabric was made that matters," Vosper said. In other words, it's more important to buy from brands that prioritise design, quality manufacturing, and craftsmanship than solely focus on purchasing a specific material.