Blackheart Crossbow String Gray/Black. These bowstrings feature GlideLock center serving which enhances durability reduces friction reduces serving separation and almost eliminates the ridges between the serving strands. The DuraWeave process includes pre-stretching the strands resulting in highly consistent string length. Each string is meticulously hand crafted to fit your crossbow Specifications for Blackheart Crossbow String 1601223: Manufacturer: Blackheart Color: Gray Black Features of Blackheart Crossbow String: GlideLock Center Serving DuraWeave Construction Pre-Streched Package Contents: Blackheart Crossbow String Blackheart 1601223: Crossbow String 1601223 Gray/Black