The correct length of 868/915MHz antennas used by FrSky R9 and TBS Crossfire is:

• for FCC 915MHz it is 75mm
• for EU/LBT 868MHz it is 80mm

From time to time FrSky has a big problem with cutting their antennas to a correct length. Good thing, you can make your own TBS Crossfire RX antennas for cheap!