The class comprised 14 submarines, U-64, U-65, U-103, U-104, U-105, U-106, U-107, U-108, U-109, U-110, U-111, U-122, U-123, and U-124. The Type IXB submarines were the most successful class of submarine in the war in terms of the total amount to tonnage sunk, with each U-boat sinking an average of over 100,000 gross register tons (GRT) during its career.[1]