Mystim Thin Finn Sound Plug. This long and smooth urethral sound is perfectly suited for the special stimulation of the penis. With some practice its 8 mm can be inserted easily into the urethra, and then create a stimulation like you have never felt before. Thin Finn is made of medical aluminum and polished neatly by hand. For extra kicks, it can be warmed on the heater or cooled in the refrigerator: it is designed to retain the temperature for an extended period of time. Mystim e-stim urethral sound length 25.0 cm diameter 8 mm e or approximately 9.84 inches by .31 inch. Material hand polished medical grade aluminum. Weight 40g e or approximately 1.41 ounces.