DISCLAIMER: Don't buy the Chinese copy of my tool, made only from aluminium. The cone which leads the seal sealing surface should be made from polyamide, like in the pictures of the tool here, to protect the teflon on the seal from damage.
This tool is made especially for installation of the front crankshaft seal on BMW M57 / M47. This tool is going to prevent damaging the crankshaft seal while installing.
In this video is shown how easy is to use it ( watch after 33:23 min ) :
https://www.youtube.com/watch?v=bHKT8OvjbKo
CRANK