ZipLine's Stranger Things, Case Study #115 string for micro sized yo-yos.
From ziplinestrings.com website: "We helped prototype a special string specifically for the KnuckleYo, and ZGRT's latest formula became the basis for the official KnuckleYo string. You'll immediately notice that the string is super thin and fairly short (likely, much different than anything you're used to), but it's an essential ingredient for getting practical use while in yo-yo mode. This string needs to be thin to get an adequate number wraps (for length) within the gap of the yo-yo to provide a decent throw and bind."
Recipe Color: White
Thickness: Micro
Formula: Nylon with polyester core thread
Quantity: 3