When I received the Big Red Rooster White Noise Sound Machine, I was impressed with the small size and loud speaker.  I was also impressed by the noises it provides, and tried a different one every night.  All of them did help me to relax prior to falling asleep.  It comes with a plug or I had the option to use batteries which I chose.  I'm very happy with this sound machine and would recommend to someone who has trouble relaxing before falling asleep. [This review was collected as part of a promotion.]