The Brodie helmet is a steel combat helmet designed and patented in London in 1915. A modified form of it became the Helmet, Steel, Mark I in Britain and the M1917 Helmet in the US. Colloquially, it was called the shrapnel helmet, battle bowler, Tommy helmet, tin hat, and in the United States the doughboy helmet. 
 
It was also known as the dishpan hat, tin pan hat, washbasin, battle bowler (when worn by officers), and Kelly helmet. The German Army called it the Salatschüssel (salad bowl)
 
"The shell has no liner or chinstrap, a solid shell that has seen service. Shell has obviously been a souvenir at some point".