If you are a CRC member and you are not Delta GM, PM or not having a Delta FC fare ticket then you can use the Elite priority security lines.

This is really a benefit in some airports i.e. ATL where the 'general' line can be very long.
In BOS there's a dedicated priority line for (a) boarding pass check and (b)security screening.
In ATL there's only a priority for the boarding pass check. Then you have to merge with everybody else for the security screening (and have to show your boarding pass again).