A Little Boy unit checked up to a bank of equipment; possibly to test/charge components within the device.
United States Army
1945-08
<a rel="nofollow" class="external text" href="http://lifestoriesbyralph.blogspot.com.au/2014/08/loading-atomic-bombs-on-tinian.html">RG-77-BT collection in the Still Photo collection of the National Archives II building in College Park, MD.</a>