Looping through dynamic sheet names - vba

Question

I am looping through a bunch of files in my folder and trying to copy a static column and paste to a master sheet. However every sheet I am looping through is a different name.
I believe this part of the code has to be changed:
xlsFiles.Sheets("Sheet3").Columns("20").Copy Destination:=wsMaster.Sheets("Sheet1").Range("A" & r).Offset(1, 0).
What can I use in place of sheets("Sheet3") ?
Here is the full code:
Option Explicit
Dim wsMaster As Workbook, csvFiles As Workbook
Dim Filename As String
Dim File As Integer
Dim r As Long
Public Sub Consolidate()
With Application
.ScreenUpdating = False
.EnableEvents = False
End With
With Application.FileDialog(msoFileDialogOpen)
.AllowMultiSelect = True
.Title = "Select files to process"
.Show
If .SelectedItems.Count = 0 Then Exit Sub
Set wsMaster = ActiveWorkbook
For File = 1 To .SelectedItems.Count
Filename = .SelectedItems.Item(File)
If Right(Filename, 5) = ".csv*" Then
Set csvFiles = Workbooks.Open(Filename, 0, True)
r = wsMaster.Sheets("Sheet1").UsedRange.Rows.Count
csvFiles.Sheets(1).Columns("col name").Copy Destination:=wsMaster.Sheets("Sheet1").Range("A" & r).Offset(1, 0)
csvFiles.Close SaveChanges:=False 'close without saving
End If
Next File 'go to the next file and repeat the process
End With
Set wsMaster = Nothing
Set csvFiles = Nothing
With Application
.ScreenUpdating = True
.EnableEvents = True
End With
End Sub

Answer 1

The answer you already got by #sktneer in the comments above.
You could shorten and "clean-up" your If section code a little, try the code below:
If Right(Filename, 5) = ".xls*" Then
Set xlsFiles = Workbooks.Open(Filename, 0, True)
r = wsMaster.Sheets("Sheet1").UsedRange.Rows.Count
xlsFiles.Sheets(3).Columns("20").Copy Destination:=wsMaster.Sheets("Sheet1").Range("A" & r).Offset(1, 0)
xlsFiles.Close SaveChanges:=False 'close without saving
End If