File:WonderSwan MP3 back.jpg

Back of a WonderSwan Color with a WonderSwan MP3 cartridge, displaying the volume control. Though shown at the Tokyo Game Show in Spring 2001, the MP3 device was cancelled. (see front)

Source

 * バンダイ、ワンダースワン用MP3プレーヤーユニット (Japanese) by Y. Fujiwa, AV Watch. 2001-04-03.