Rollerball Pens
Rollerball pens are similar to ballpoint pens in that they both operate by a tiny ball distributing ink onto the paper, but the ink in a rollerball pen is water based, like you would get in a fountain pen. This means that a rollerball pen needs a cap, to stop the ink from drying out, and also it means that the writing style is much more fluid than a ballpoint, while being much easier to maintain than a fountain pen.
Rollerball pens are a half way compromise between the two, taking the ease of use of a ballpoint, and combining it with the elegant writing style of a fountain pen.
Uni-Ball
Uni-Ball UB-157 Eye Fine Liquid Ink Rollerball Pens - Assorted Colours (Blister of 3)
Multipack of uni-ball Eye Fine UB-157 Liquid Ink Rollerball Pen
Uni-Ball
Uni-Ball UBA-188-L-AIR Rollerball Pens - Assorted Colours (Blister of 3)
Multipack of Uni-Ball UBA-188-L AIR Rollerball Pen
Schneider
Schneider Topball 847 Rollerball Pen
Moleskine
Moleskine X Kaweco Rollerball Pen - Blue
Faber-Castell
Faber-Castell Free Ink Needle Rollerball
Schneider
Schneider Topball 857 Rollerball Pen
Pentel
Pentel R50 Rollerball Pen
Uni-Ball
Uni-Ball UB-157 Eye Fine Liquid Ink Rollerball Pens - Assorted Colours (Blister of 8)
Multipack of uni-ball Eye Fine UB-157 Liquid Ink Rollerball Pen
Schneider
Schneider Topball 811 Rollerball Pen
Pentel
Pentel EnerGel XM Retractable Rollerball Pen - 0.7mm - Black (Pack of 5)
Multipack of Pentel EnerGel XM Retractable Rollerball Pen
Schneider
Schneider One Hybrid N Rollerball Pen
Hugo Boss