NRG-2 18 is $12.50 from TW. Compare with: Ashaway Dynamite 17, Zyex/Nylon, 1.24mm, 147 stiffness, 13.72 lbs lost Head Synthetic Gut PPS 18, Nylon, 1.16mm, 176 stiffness, 11.93 lbs lost Tecnifibre NRG2 18, Nylon/Polyurethane, 1.17mm, 181 stiffness, 9.86 lbs lost (RSI data: 62 lbs reference tension, fast swing speed) The NRG-2 has a bit better tension retention, but it's a touch thicker and stiffer. It's also $8.55 more expensive per pack. The Head string costs $3.95. One can get a pack of Ashaway Dynamite 17 and a pack of Head Synthetic Gut PPS 18 for the same price as one pack of NRG-2 18 — or less if you get the 5+ packs price for the Dynamite. In that case it would be about a dollar cheaper for the two packs versus one pack of NRG-2. Or one could buy three packs of the Head string for the price of one pack of NRG-2 18. Food for thought.