Complex sentence: Typically protected cruisers displaced from 2,500 to 7,000 tons, and were armed with up to a dozen single guns of between 3.9 and 6 inches (100 to 152 mm) in calibre.
Split into simpler sentences: Typically protected cruisers displaced from 2,500 to 7,000 tons. The armament of protected cruisers was up to a dozen single guns of between 3.9 and 6 inches (100 to 152 mm) in calibre.