The BBManager and the Firmware update where released compressed in rar format.
Zip format is already integrated in Windows, rar needs to download and install an external utiity.
Nowadays more or less all “free” utilities come with some form to advertising.
Besides this, the differences between rar and zip formats in terms of final size are not dramatic.
Here you are my tests made with BBManager an Firmware:
BBmanager ( rar) 43.371 KBytes
BBmanager (zip) 43.360 KBytes
Firmware ( rar) 279 KBytes
Firmware (zip) 302 KBytes
So, I’m asking you to consider to switch to the Zip format for future files distribution.