4D stands for 4 directional braiding.
It is contructed using four braided fibres of superlight S-glass fiber wrapped in an aluminum alloy sheath.
The fibres are aligned at 0, 90, 22 and-22û orientations which enables stresses to be supported in multi-directions whereas standard carbon sheets are only orientated in one direction. This means that one layer of 4D material has the equivalent properties to four layers of standard carbon layed up at orientations. Consequently 4D material is four times more effective than standard carbon. Furthermore, by using one layer, 4D is also softer and less bulky than 4 layers of carbon.
At 5 and 7 o'clock the multi-directional properties of the 4D braided cloth help stabilize the torsional twist at key points of the racquet.
At 3 and 9 o'clock one layer of 4D braided cloth provides the torsional stability previously only achievable with several layers of carbon fibre. As a result of only one layer being used instead of several this softer material also provides superb touch and feel at ball contact.
Dunlop Aerogel 4D 300 (3Hundred) Lite Racquet