Check out the video of Patrice Kuchna, known as the Human Machine, as he conducts string durability testing for Tecnifibre: http://www.tennis-warehouse.com/vlogpageFO.html?ccode=THEMACHINE This guy breaks gut in about 60 hits. Most multis break after about 100-120 hits. Tecnifibre NRG2 17 lasted over 160 hits. A poly lasts about 220 hits. Chris, TW.