This is my third Rotring-pen, the first one (Rotring 600 0.7mm) I still have as everyday use at work for over 5 years now without any problem.
The Rotring 600 3in1 has black + red ink and 0.5mm stift.
You can use D1 ballpoint refills (Jetstream SRX-200-05 works) if you dont want to use Rotring-refills. Just make sure not to order/use the plastic versions since they are diff. in size.