Sega Neptune

The Sega Neptune is a one-in-one Mega Drive/Genesis and 32X combination just like the Multi-Mega/CDX is a Mega Drive/Genesis and Mega-CD/Sega-CD combination. It is also compatible with the Mega-CD/Sega-CD Model 2.
 * Release Date: November 23rd, 1995.
 * Units Sold:5 Million Units Sold.
 * Discontinued:April 13th, 1998.

Sega Neptune X
On February 5th 1997, Sega released a Sega Mega Drive/Genesis + Mega-CD /Sega-CD + 32X combination.