The model comes armed with a force blade which is attached to an arm that can be modelled on the left or right of the Dreadnought, the other arm can be chosen from any Contemptor Dreadnought arm option, available separately.
Rules for the Osiron Pattern Contemptor Dreadnought can be found in The Horus Heresy Book Seven: Inferno.
This resin kit is supplied with a 60mm round base.