I like the double ended Hegars... they are gently curved... matching the curve of my erection.
The ones with eh J shaped end are just awkward as hell.
One thing Neck did not mention... they come in various sizes and lots of guys into sounding want to stretch their urethra to accommodate larger sounds. If so, proceed slowly.
Always star with a smaller sound, Even it its only been a day or so, you will find it easier to get the smaller one in intially...and, after you are relaxed and comfortable, move up ONE sound size at a time.... Do not force a larger sound down... while you may be able to go up a size or two in a single session... do not move up to a larger size until you find you can Start a sounding session comfortably with the next size up.
Also... you want to be careful... you can literally lose a sound... it can slide up pretty far- well inside the cock and into the bladder.
You generally do NOT want to introduce sounds into the bladder as it may impair function of the urinary sphincter, and significantly increases the danger of a bladder infection.
If you also happen to have a PA or apadravya piercing- then you can get something called a Prince's Wand... Which is a sound held in place by a stud thru the piercing.
Unlike true sounds, Prince's wands are usually drilled thru their length, which enable you to both piss and cum with the sound in place. They are generally custom made to order and can be as wild as your imagination.
Check them out at Steelwerks Extreme