+.It Fl z Ar compression level
+Compress every block to be written on the tape using zlib library. This
+option will work only when dumping to a file or pipe or, when dumping
+to a tape drive, if the tape drive is capable of writing variable
+length blocks. You will need at least the 0.4b22 version of restore in
+order to extract compressed tapes. Tapes written using compression will
+not be compatible with the BSD tape format. The (optional) parameter
+specifies the compression level zlib will use. The default compression
+level is 2.