Poly Tour Rev is the latest addition to Yonex's already impressive line of polyester strings. Rev is a co-polyester built with spin potential in mind. Its octagonal cross-section combined with Silicone Oil Infused Filament Technology (SIF) allows the string to move easily and enhance the snap back needed for topspin creation while also providing a little bit more bite on the ball. Like all polyester strings, it has a firm feel to it but at the same time is on the more comfortable side compared to some of its rivals.