These are the only loopback plugs designed and manufactured specifically for loopback testing of audio ports and headset connectors, built using the circuit specifications outlined by Google.
The plugs can be used to meaure round-trip latency and autocorrelation with software such as OboeTester.
OboeTester is a free and open source software that can be used to measure device latency and glitches on Android devices when paired with PassMark's Audio Loopback Plug.
OboeTester can be built within Android Studio. For a guide on how to download and run OboeTester within Android Studio, view the Specifications Page.