Discraft says this about the Surge SS: Discraft Stability Rating: Z-Line 1.6; ESP FLX 1.6
A max distance driver for players who don't have quite enough snap to maximize the original Surge's potential. The Super Straight Surge SS delivers all the glide that players have come to expect from a Surge, with a straighter edge to enhance controllability at slower speeds. Goes a long way with less effort!
About Z-Line Plastic
Most durable, truer flights, last 2-3 times longer.