The "Trygg" class had a fairly substantial armament for being small ships of relatively early design. Each carried two 76 mm main guns, an Oerlikon 20mm autocannon for anti-aircraft defence, as well as two twin 45 cm torpedo tubes. Combined with a reasonable speed of 25 knots (46 km/h) and excellent manoeuvrability this enabled the "Trygg" class vessels to operate effectively both in cooperation with other naval units and on their own. Their operations were however limited mostly to coastal waters as they were not very seaworthy or stable platforms, having been constructed for operations close to land. In the fighting that followed the German invasion on 9 April 1940 the "Trygg" class would see first line action as these ships were often all that was available to the Norwegian forces.