ange-ftp-binary-hash-mark-size

ange-ftp-binary-hash-mark-size is a variable defined in `ange-ftp.el'.
Its value is

nil

Documentation:
Default size, in bytes, between hash-marks when transferring a binary file.
If nil, this variable will be locally overridden if the FTP client outputs a
suitable response to the HASH command. If non-nil, this value takes
precedence over the local value.

You can customize this variable.