All the advantage of a multifilament and monofilament in one string and the first string with variable flex. It produces more control on hard shots and more comfort on soft shots. No need for hybrids-M2 provides perfectly balanced performance. M2 is a combination of two polyester fibers. It features 10 inner fibers of different shapes and sizes that are surrounded by an outer sheath of a new proprietary Luxilon co-polymer polyester which gives M2 its unique playing characteristics. Use the 16L gauge for added playability.