Format Timespan in DataGrid

I will like if possible, to format a timespan in a datagrid.
From this: 04:15:17.1910000
To: 04:15:17.19
<asp:Label ID="Label2" runat="server" Text='<%# String.Format("{0:hh:mm tt}",DataBinder.Eval(Container.DataItem,"duration")).ToString()%>'></asp:Label> Thanks!