Container ships are cargo ships, also known as Cellular vessels, that carry all their load in truck size inter modal containers. Container ship capacity is measured in twenty-foot equivalent units (TEUs). Typical loads are a mix of twenty-foot and forty-foot (FEUs) ISO standard containers. Containerization is now a common means of transport carrying most of sea going non bulk cargo. Feeders are small container ships less than 3000 TEUs and generally operate between smaller container ports.