Final answer:
Lululemon's products primarily use Lycra for shape retention, a material known for its elasticity and durability, especially suitable for athletic wear.
Step-by-step explanation:
Essentially all of Lululemon's products have Lycra for shape retention. Lycra is a brand name for a type of synthetic fiber known generically as elastane or spandex. This material is known for its exceptional elasticity and is used in various types of clothing to provide stretch and a figure-hugging fit while also maintaining the shape of the garment over time. It's particularly favorable in athletic wear, which is Lululemon's specialty, because it allows for freedom of movement and can hold up to the stress of physical activities without losing shape.