# Setup session options
$sessionOptions = New-Object WinSCP.SessionOptions -Property @{
    Protocol = [WinSCP.Protocol]::Sftp
    HostName = "xxx.xxx.xxx.xxx"
    UserName = "joe"
    Password = "joebloggs"
    SshHostKeyFingerprint = "ssh-rsa 1024 01:07:da:11:22:33:44:55:66"
    FtpMode = [WinSCP.FtpMode]::Active
}

$session = New-Object WinSCP.Session

try
{
    # Connect
    $session.Open($sessionOptions)

    # Download files
    $transferOptions = New-Object WinSCP.TransferOptions
    $transferOptions.TransferMode = [WinSCP.TransferMode]::Binary

    $transferResult = $session.GetFiles("/*", "C:UsersUserDropboxRockarDataSystem DataRaw FeedsStock"+$a+"", $False, $transferOptions)

    # Throw on any error
    $transferResult.Check()

    # Print results
    foreach ($transfer in $transferResult.Transfers)
    {
        Write-Host ("Download of {0} succeeded" -f $transfer.FileName)
    }
}
finally
{
    # Disconnect, clean up
    $session.Dispose()
}