This is the Hardened model, a concoction of polyamide & glass fibre, promising 1500 hours of play time. In fact, this is the manufacturer's most durable but it feels very light & accommodating. It's been played for less than an hour, offering a different feel nevertheless. Despite the accolades, many of you out there are actually disturbed by the asymmetrical outline just by looking at it; how can an odd ball like this make a difference? That's the reason I'm trying it.