The Troglite helmet isn't entirely suitable for caving, it's just a site helmet with a chinstrap retainer and won't provide much protection in a fall - BS EN 397 is for protection against falling objects, and the chinstrap will be designed to break under a minimal load so that it doesn't hang the wearer up. Look for something with UIAA certification or that meets BS EN 12492.
Speaking though as someone who from time to time wears a cut down site helmet for caving! :-[