"AS TRANSPARENT AS POLISHED GLASS AND AS CLEAR AS SPARKLING CRYSTAL" DESCRIBES GX SOUND. That description was intended from the very beginning and, in fact, ref lects the properties of the head material itself (glass and crystal ferrite). The GX-221D employs two of these GX Heads plus top quality parts for absolute,,mechanical dependability and lasting GX performance. A Tape Selector Circuit enables the employr&nt ofr low noise tape for a high frequency response coverage to 25,000 Hz. Sound-on-sound recording for profgssional or fun use. Automatic and manual reverse playback, Automatic Stop and Shut-Off, Pause Control. Tape/Source Monitor Switch for instant dual monitoring, Din Jack.