Some of the RF handheld transmitters and panel antennas like those pictured above from Linx Technologies have a colored band around the antenna that help the user to identify the center band frequency.
Here is a chart that shows the colors/bands they represent.
Applicable Part Numbers
ANT-868-PW-LP-ND ANT-433-PW-LP-ND ANT-2.4-CW-RH-SMA-ND ANT-2.4-CW-RH-RPS-ND ANT-916-PW-QW-ND ANT-916-CW-RH-ND ANT-868-CW-RH-SMA-ND ANT-433-CW-RH-SMA-ND ANT-916-CW-RH-SMA-ND ANT-916-CW-QW-ND ANT-2.4-PW-QW-UFL-ND ANT-868-CW-QW-SMA-ND ANT-868-CW-QW-ND ANT-433-PW-QW-ND ANT-2.4-CW-QW-RPS-ND ANT-433-CW-QW-SMA-ND ANT-916-CW-HD-ND ANT-433-CW-HD-ND ANT-433-CW-QW-ND ANT-2.4-CW-HW-SMA-ND ANT-418-CW-QW-ND ANT-916-CW-HW-ND ANT-868-CW-HW-ND ANT-868-CW-HW-SMA-ND ANT-916-PW-LP-ND ANT-418-PW-LP-ND ANT-ELE-S01-005-ND ANT-868-PW-QW-ND ANT-2.4-PW-QW-ND ANT-315-CW-RH-SMA-ND ANT-418-CW-RH-ND ANT-418-CW-RH-SMA-ND ANT-2.4-CW-CT-RPS-ND ANT-916-CW-QW-SMA-ND ANT-916-PW-QW-UFL-ND ANT-2.4-CW-QW-SMA-ND ANT-418-CW-QW-SMA-ND ANT-433-CW-HD-SMA-ND ANT-2.4-CW-HW-ND ANT-315-CW-HW-SMA-ND ANT-315-CW-HW-ND ANT-2.4-PW-LP-ND ANT-315-PW-LP-ND ANT-ELE-S01-010-ND ANT-418-PW-QW-ND ANT-868-CW-HD-SMA-ND ANT-433-CW-HW-SMA-ND ANT-418-CW-HW-ND ANT-418-CW-HW-SMA-ND ANT-1.4-CW-HW-ND ANT-418-CW-HD-ND ANT-433-PW-QW-UFL-ND ANT-315-CW-HD-ND ANT-ELE-S01-006-ND ANT-ELE-S01-008-ND ANT-315-CW-RH-ND ANT-DB1-RMS-RPS-ND ANT-916-ID-1000-RPS-ND ANT-916-ID-1000-SMA-ND ANT-2.4-ID-1000-RPS-ND ANT-868-ID-1000-SMA-ND ANT-2.4-ID-1000-SMA-ND ANT-2.4-ID-2000-SMA-ND ANT-916-ID-2000-SMA-ND ANT-916-ID-2000-RPS-ND ANT-868-ID-2000-SMA-ND ANT-2.4-ID-2000-RPS-ND ANT-2.4-CW-CT-SMA-ND ANT-868-PW-QW-UFL-ND ANT-916-CW-HW-SMA-ND ANT-433-CW-RH-ND ANT-433-CW-HW-ND ANT-868-CW-RH-ND ANT-418-PW-QW-UFL-ND ANT-1.4-CW-HW-SMA-ND ANT-DB1-RMT-RPS-ND ANT-DB1-RMT-TNC-ND ANT-DB1-RMS-TNC-ND ANT-868-ID-2000-RPS-ND ANT-2.4-OM-CM-01-N-ND ANT-868-CW-HD-ND
ANT-868-PW-LP ANT-433-PW-LP ANT-2.4-CW-RH-SMA ANT-2.4-CW-RH-RPS ANT-916-PW-QW ANT-916-CW-RH ANT-868-CW-RH-SMA ANT-433-CW-RH-SMA ANT-916-CW-RH-SMA ANT-916-CW-QW ANT-2.4-PW-QW-UFL ANT-868-CW-QW-SMA ANT-868-CW-QW ANT-433-PW-QW ANT-2.4-CW-QW-RPS ANT-433-CW-QW-SMA ANT-916-CW-HD ANT-433-CW-HD ANT-433-CW-QW ANT-2.4-CW-HW-SMA ANT-418-CW-QW ANT-916-CW-HW ANT-868-CW-HW ANT-868-CW-HW-SMA ANT-916-PW-LP ANT-418-PW-LP ANT-ELE-S01-005 ANT-868-PW-QW ANT-2.4-PW-QW ANT-315-CW-RH-SMA ANT-418-CW-RH ANT-418-CW-RH-SMA ANT-2.4-CW-CT-RPS ANT-916-CW-QW-SMA ANT-916-PW-QW-UFL ANT-2.4-CW-QW-SMA ANT-418-CW-QW-SMA ANT-433-CW-HD-SMA ANT-2.4-CW-HW ANT-315-CW-HW-SMA ANT-315-CW-HW ANT-2.4-PW-LP ANT-315-PW-LP ANT-ELE-S01-010 ANT-418-PW-QW ANT-868-CW-HD-SMA ANT-433-CW-HW-SMA ANT-418-CW-HW ANT-418-CW-HW-SMA ANT-1.4-CW-HW ANT-418-CW-HD ANT-433-PW-QW-UFL ANT-315-CW-HD ANT-ELE-S01-006 ANT-ELE-S01-008 ANT-315-CW-RH ANT-DB1-RMS-RPS ANT-916-ID-1000-RPS ANT-916-ID-1000-SMA ANT-2.4-ID-1000-RPS ANT-868-ID-1000-SMA ANT-2.4-ID-1000-SMA ANT-2.4-ID-2000-SMA ANT-916-ID-2000-SMA ANT-916-ID-2000-RPS ANT-868-ID-2000-SMA ANT-2.4-ID-2000-RPS ANT-2.4-CW-CT-SMA ANT-868-PW-QW-UFL ANT-916-CW-HW-SMA ANT-433-CW-RH ANT-433-CW-HW ANT-868-CW-RH ANT-418-PW-QW-UFL ANT-1.4-CW-HW-SMA ANT-DB1-RMT-RPS ANT-DB1-RMT-TNC ANT-DB1-RMS-TNC ANT-868-ID-2000-RPS ANT-2.4-OM-CM-01-N ANT-868-CW-HD
CMD-HHLR-418-MD-ND CMD-HHLR-433-MD-ND OTX-418-HH-LR8-MS-ND CMD-HHCP-418-MD-ND CMD-HHCP-433-MD-ND CMD-HHLR-315-MD_-ND OTX-433-HH-CP8-MS-ND OTX-418-HH-CP8-MS-ND OTX-433-HH-CP8-HS-ND OTX-433-HH-LR8-MS-ND CMD-HHCP-315-MD-ND OTX-315-HH-CP8-MS-ND OTX-315-HH-LR8-MS-ND OTX-433-HH-LR8-HS-ND
CMD-HHLR-418-MD CMD-HHLR-433-MD OTX-418-HH-LR8-MS CMD-HHCP-418-MD CMD-HHCP-433-MD CMD-HHLR-315-MD OTX-433-HH-CP8-MS OTX-418-HH-CP8-MS OTX-433-HH-CP8-HS OTX-433-HH-LR8-MS CMD-HHCP-315-MD OTX-315-HH-CP8-MS OTX-315-HH-LR8-MS OTX-433-HH-LR8-HS