Hillrom - Welch Allyn GS 777 Wall Transformer Only - No headsAccurate diagnostics kept securely within reach. You choose any 3. 5v heads to suit your needs (see Ophthalmoscope and Otoscope Sections). Features; Up to 54% more energy efficient than previous 767 models Handle based rheostats for quick light intensity adjustments Offers the flexibility to add on as you go OptiSense sensor automatically turns handles on and off when removed and replaced from the cradle Advanced coil cords stretch up to 12 feet