AddADay Echo Oscillator Roller Rechargeable Muscle Massager Vibrator Vibration The Echo is a rechargeable oscillator. The Echo roller can be used alone or if you prefer more cushion it can be placed in a hollow foam roller with a diameter of 3 7/8" or larger. The Echo can also be used to oscillate any muscle group in a static or dynamic position. Echo can be used on various parts of the body. Charging time is 3-4 hours for 1.5-2 hour usage. There are three different speeds for different intensities, low intensity, high intensity and varied intensity. The roller will automatically shut off after 10 minutes. The Echo has a diameter of 3 3/4" and is 11 7/8" long Excellent Overall Like New Condition No Original Packaging A Couple Indents Around Piece(Pictured) Otherwise No Deep Marks or Damages Please See All Photos for Ultimate Description.