This Retro 51 Cape-less Refill is totally compatible with all the Tornado pens.
Retro 51 Cape-Less Refill
This is one is a black Schmidt P8126 Cap less System roller ball pen refill. This is the short model version, the stainless steel tip has a 0.6 mm ceramic ball. It has a one year cap-off time, meaning that the ink does not dry out even if left uncapped for one year.