New Corrugated Technology Corrugated Rails are incorporated into the throat area of the racquet. These corrugated rails increase stiffness up to 12% vs. conventional racquet design. HEAD patented twin-tube technology has been strategically positioned in the head of the racquet. This provides maximum stability on every shot! Microgel Head Size: 106 sq. in. / 684 sq. cm. Length: 22 inches / 56 cm Unstrung Weight: 165g / 5.8oz Strung Weight: 186g / 6.6oz Balance: 11.625in. 5 pts Head Heavy Swingweight: 155 Stiffness: CT Stiff Beam Width: 21 Composition: Microgel/Metallix Graphite Grip Type: Hydrosorb Wrap String Pattern: 16 Mains / 16 Crosses Mains skip: 8H Two Piece Shared Holes: 5H,6H,7H,9H String Tension: 28-34 pounds This new space-age technology has allowed HEAD to design the a solid hitting racquet! MicorGEL is a revolutionary silicone-based material that can support up to 4,000 times its own weight. This low density material is injected between the graphite layers throughout the entire frame. Upon ball impact HEAD MicroGEL compresses, absorbing and dispersing the impact to the entire frame, then returns quickly to its original shape.