Possibly due to their position of relative strength in the market at the time, Sony would wait until 1997 before making any changes to their controller. The Dual Analog controller was released as an alternative to the bundled controller in April 1997, but was only on the market for about six months before being replaced by the DualShock controller. Unlike Sega with their 3D Control Pad, Sony replaced the controller that came bundled with the PlayStation. The Dual Analog controller was a relatively simple modification, adding a pair of analog sticks at the bottom of the existing controller design, and DualShock just extended this to include vibration. Incredibly, this same basic layout has persisted through all subsequent PlayStation consoles, an unbroken line stretching back more than two decades.