Nach Dokumenten filtern

Hallo Zusammen,

ich möchte in allen Dokumentenbibliotheken nach Docx etc filtern und habe folgendes Script. Leider werden mir alle Items angezeigt, wie setzte ich einen Filter?

Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue

Function GetFiles($Folder)
{
   Write-Host "+"$Folder.Name

    foreach($file in $Folder.Files)
 { 
     Write-Host "`t" $file.Name
 }
  #Loop through all subfolders and call the function recursively
     foreach ($SubFolder in $Folder.SubFolders)
        {
      if($SubFolder.Name -ne "Forms")
      { 
       Write-Host "`t" -NoNewline
    GetFiles($Subfolder)
    
   }
  }
 }

#Get the Site collection
$Site= Get-SPSite http://sharepoint.de
       #Loop throuh all Sub Sites
       foreach($Web in $Site.AllWebs)
       {
     Write-Host "-----------------------------------------------------"
     Write-Host "Site Name: '$($web.Title)' at $($web.URL)"
  Write-Host "-----------------------------------------------------"
     foreach($list in $Web.Lists)
  {
     #Filter Doc Libs, Eliminate Hidden ones
   if(($List.BaseType -eq "DocumentLibrary") -and ($List.Hidden -eq $false))
      {
       GetFiles($List.RootFolder)
      }
  }
    }