Standard cassette machines play audio cassettes at 15/16 inches per second (ips) and 1-7/8 ips (4-track and 2-track, respectively).  These portable machines are equipped with rechargeable batteries, an electrical cord, variable speed control which permits speeding up or slowing down playback speed.

 

Easy Cassette Machines play audio cassettes at only 15/16 ips (4-track only) and, lacking batteries, must be plugged into an electrical outlet.  These machines lack variable speed control but automatically rewinds cassettes and automatically changes tracks.