APC-7 connector

APC-7 connectors are advantageous because they have a low reflection coefficient, make repeatable coaxial connections, and are genderless.

[1] The connectors are expensive, so they are seldom used outside the laboratory where their cost can be justified by their accuracy and convenience.

Due to their high cost, their 18 GHz frequency limitation, and new laboratory practices,[note 1] the connectors are now uncommon.

Modern low-frequency microwave equipment often uses the less expensive 3.5 mm (26.5 GHz) connector.

[4] "APC" stands for Amphenol Precision Connector and "-7" for 7 millimetres.