Determines max bytes per second client can use.

A Long value.  

object.MaxTransferRate [= value]

The MaxTransferRate Property syntax has these parts:

MaxTransferRate defines how much maximum bandwidth user can use. It is presented as 'bytes per second', both for upload and download. When set to 0 (default value), user has no bandwidth limit.

You can change this property at any time, and user will be affected immediately. You will notice that clients that show 'bytes per second' rate may show inconsistent values, since most of them show average bps rate - rather than current bps rate. However, if you define such rate when user connects, and you don't change it anymore, it will be shown properly in most client applications.
For example, if you want to restrict only download for the user, you can set MaxTransferRate property from within DownloadFile event, and then set it back to 0 from within TransferComplete event.

You can always refer to BytesDownload and BytesUpload properties to see how much user transferred in current session.

To get correct kilobytes and megabytes per second values, you should multiply bps rate with 1024 or 1024^2, not 1000.