This string is PREMIUM 100% Cotton Type 6 Standard Long and comes in a 100 pack. About Yo-Yo String: Material: Yo-yo string is usually made of 3 materials (either a single material or a blend): ● Cotton: ● Polyester: Longer lasting than Cotton. ● Nylon: Longer lasting and stiffer than Polyester. 100% Cotton is basic yo-yo string. Slick is a blend of 50% Cotton and 50% Polyester or Nylon. Slick is a bit heavier than 100% Cotton and is more durable. 100% Polyester string is a bit heavier and a bit more flexible than Slick. It is more durable and both Slick and Cotton. 100% Nylon is slightly stiffer than Polyester and is more durable. It really flows through the air so for slack, whip, or suicide tricks the loops created stay open and move fast.