I have been dual sporting with them for a year & a half on my DRZ & deformed two sets of RAM balls so I ordered these from http://www.hotrodwelding.nl/home.php;
They came with electrical shrink tube to cover the ball but that got misshaped on the first ride so I used them without it for a few months. They work great but I get alot of vibration at certain RPMs & loads so I have since been experimenting.
I put a rubber washer under the ball where it mounts to the bars, another under the head of the bolt inside the ball & have been experimenting with rubber bumpers & stoppers on the mirror stalk ball. This seems to be the best idea so far (similar to the one second from the left, without the long stem);
After I figure the best size, I may also figure adding some to the hotrodwelding ball or the Ram arm.