This video illustrates the VAS Shapeshifter and how it works. This covers both the 868 and 915MHz frequency for Crossfire.
Where to buy:
https://www.readymaderc.com/products/details/vas-shapshifter-selectable-gain-900mhz-antenna
https://www.team-blacksheep.com/products/prod:vas_shapeshifter_900
