Tecnifibre`s NRG2 Tennis String Reel in Natural is one of the last multifilament strings seen on the pro circuits. The string uses Tecnifibre`s Elastyl fibers to supercharge NRG2 with 12% more power than the standard synthetic polyamide string. In addition to the extra pop, NRG2 uses SPL, or Silicon Pyrogene Lubritec as an abrasion resistant coating to improve durability and resistance to notching. The companies PU Inside technology provides up to 400% elasticity to give players a comfortably dampened feel, well balanced between power and control. As far as multifilaments go, you would be hard pressed to find a synthetic string as powerful as NRG2.