Black Knight ION Quartz PSX Squash Racquets : For intense power and a quicker attack on the ball, pick up the Black Knight ION Quartz PSX squash racquet. Power Surge bars that sandwich the throat and shaft of the racquet provide extra stiffness and vibration dampening qualities. Its weight and balance make it quick to volley with. Prestrung with Ashaway PowerNick 19. Thin-K slimmer frame creates a more aerodynamic feel. Thermal Core creates a stronger frame without irregularities for higher durability.