It's the one.
More and more riders and tire manufacturers are moving away from ultra-narrow tires in favor of wider tires with better grip and low rolling resistance. Schwalbe claims its One Road Tubular Tire is the fastest and most reliable tire it's designed to date. To put an exclamation to this point, it set up a dedicated factory with fixed vulcanization and production units that are used exclusively for the One.
Schwalbe used a new compound, OneStar, to achieve extremely low rolling resistance in the One tire. OneStar is a triple compound that was developed using new polymers that provide better tradeoffs and fewer compromises between rolling resistance, wet grip, and durability.
The Schwalbe One Tire - Tubular is very light. The 22mm tire weighs in at 260 grams. This places it as the lightest of the Schwalbe road line. It is also available in a slightly heavier 24mm width. Both sizes come in Black.