My slave's urethra has already been stretched really wide, so now he has to experience both width and depth sounding. I push in a size 11 steel sound first to make sure the urethra is open, and then I use a 40cm (16 inch) long 11mm silicone sound to really challenge him on depth. I pass it into his urethra until every last millimetre has been swallowed up, and then take pleasure in tormenting him as I slide it in and out of his stretched hole!