Seemingly against the laws of nature, lightweight with the power to stop big fish are not words commonly found together in a sentence. Thunnus CI4 takes a page from Shimano's bicycle division and uses carbon materials in high-impact situations in response to anglers wanting a reel with bait-running functionality but in a lightweight body. Thunnus CI4 is up to 7 ounces lighter than its predecessor without sacrificing any power and incorporates new drag systems for the main drag as well as the baitrunner drag.