This particular model is equipped with a urethral sounding dilator. It is made of smooth, flexible medical grade silicone, which click into the bottom of the device and go into the opening of the urethra. The total length of the dilator is 20.5 cm (8.07 "), the insertable length is 20 cm (7.87"), and the diameter is 3.5 mm (0.137 ").