FF stands for larger than average. This term refers to items of clothing that are both large and loose fitting. Larger sizes are available for men and women. Men's sizes range from XL to 5XL, while women's sizes range from XS to 8X. Loose fitting clothes are also called "agile fit" or "athletic wear." These descriptions apply to shirts, pants, jackets, and other garments for men and women. Agile fits are most commonly found in athletic wear because this category requires no specific tailorings like dress shirts do. As you can guess from the name, agile fits are very flexible and able to move with you as you exercise. Athletic wears are available in different materials such as cotton, polyester, and wool. Wool is the most durable material and will last longer if you don't mind spending more money on clothes. Cotton is the cheapest option but will likely get dirty fast since it's natural fiber and won't hold up as well when it comes to stains. Polyester is a plastic-like material and tends to be dry feeling.