The Mahan-class destroyers of the United States Navy were a series of 18 destroyers of which the first 16 were laid down in 1934.
The last two of the 18, Dunlap and Fanning (this pair laid down in 1935), are sometimes considered a separate ship class.
Dunlap and Fanning were the first US destroyers to use enclosed forward gun mounts rather than shields; their light pole foremast and lack of a mainmast visibly distinguished them from the Mahans.
There are three ships in this download:
USN_Dunlap_1941_LOD, as built.
USN_Dunlap_1942_LOD, with 7 x 20mm AA guns replacing the 50cal MG and number 3. 5 inch gun removed.
USN_Dunlap_1944_LOD, with 2 x 2 40mm AA guns replacing 2 x 20mm AA guns, Radars and Depth Charge Throwers.
Cheers
Stuart