Black Code is an excellent new string from Tecnifibre's Polyester Range. 
It features a 3rd generation polyester with a pentagonal cross-section and a co-polyester core for ultimate durability.

Its key benefits are :-

Flexibility -  less shock on impact compared to 2nd generation polyesters.
Tolerant - less risk of premature breakages from off center hits due to wider sweetspot.
Spin - more spin is generated due to pentagonal structure

This pack contains one set of string which is allows you to string one racket.

This string is an ideal string for hard hitters and chronic string breakers. It offers a more flexible feel than many other polyester strings on the market, producing less shock to the player. It is also an ideal string to be used as the mains in a Hybrid set.

This is a monofilament string which is a solid one piece construction of extruded polyester. Polyester strings are very durable, however they offer less feel and power to the player than other strings. A racket strung with Polyester generally loses tension more quickly, therefore many players have them strung at a higher initial tension.