The Yonex EZONE ACE Sky Blue Tennis Racquet 7th Generation Prestrung is perfect for beginners to intermediate players looking for power and comfort. The Yonex EZONE ACE offers many of the technologies available in other EZONE racquets but in a less expensive, prestrung model.Technology:Isometric - Developed over 30 years ago, the Isometric design increases the sweet spot by 7%. Compared to a conventional round frame, a square-shaped Isometric racquet generates a larger sweet spot by optimizing the intersection of the main and cross strings. Isometric technology delivers greater control without sacrificing power.Oval Pressed Shaft - First introduced in 1969 with the T-7000 - Yonexes first aluminum tennis racquet - the Oval Pressed Shaft (OPS) is still incorporated into their most popular racquet series today. The Oval Pressed Shaft is designed to give players more spin, control, and feel. The shaft flexes at impact, increasing dwell time and minimizing vibrations.Aero Shape Design - For a plush feel. An inverted frame design with a thinner frame face results in a softer racquet.The Yonex philosophy has always remained the same: to contribute to the world through innovative technology and the highest-quality products.