One alternative is a trackball, in effect an upside-down mouse with the roller ball on top.

On each CT section, right and left lung parenchyma were delineated using the roller ball of the computer.

But unlike other roller balls, this one can be filled with regular fountain pen ink by dipping it directly into a bottle.

The best feature of the Mega, he said, is the way its roller ball can use a range of fountain pen inks.

If you use the roller ball to glide over to the boy, he crawls into a corner and cowers.

I did have the roller ball don't you?

Well that's a roller ball yes.

A container with a roller ball permits direct application.

I had to replace the ball, the little roller ball.

The Parker 100 was offered in the form of a fountain pen, roller ball, ballpoint, and pencil.