The paper：

The RV1 circuit-breakers use a mechanical operating mechanism. The operating mechanism is of simple conceptionand use and can be customised with a wide rangeof accessories which are easy and rapid to install.

The RV1 Vacuum circuit-breakers use vacuum interrupters embedded in resin poles.
Embedding the interrupter in resin makes the circuit-breaker poles particularly sturdy and protects the interrupter against shocks, accumulation of dust and humidity.