Circular Knit is the most suitable knit structure for Compression wear with a 360 degree stretch compression. Exclusive to 2XU. 50 Denier Lycra, compared with 30/40 Denier used by our competitors. Denier represents the thickness of the yarn. A thicker yarn delivers a stronger compressive power. This fabric provides the most compressive tight on the market. The graduated compression of the tight is fundamental to remove all the waste byproducts the body produces during high active sport, which cause fatigue. The extra push of blood from the ankles towards the heart allow this tight to give you another level of performance and will allow you to perform longer with less fatigue.