protected override void SetComboBox() { var lengthDictinary = LengthConverter.NiceComboboxDataRepresentation(); comboBox_FromUnit.DataSource = new BindingSource(lengthDictinary, null); comboBox_FromUnit.DisplayMember = "Key"; comboBox_FromUnit.ValueMember = "Value"; comboBox_ToUnit.DataSource = new BindingSource(lengthDictinary, null); comboBox_ToUnit.DisplayMember = "Key"; comboBox_ToUnit.ValueMember = "Value"; }