This long and smooth urethral sound is perfectly suited for the special stimulation of the penis. With some practice its 6 mm can be inserted easily into the urethra, and then create a stimulation like you have never felt before. The Slim Finn is 15 cm long, 6 mm in diameter and crafted from hand polished medical grade aluminum. This e-stim urethral sound is bi-polar and you will require an e-stim device like the Tension Lover, or the Mystim Pure Vibes to activate the poles, not included. Sold separately.