The Shure A89U adapter is used to shorten the footprint of the three VP89L, VP89M, and VP89S microphone models by up to 6" (15.24 cm). The adapter is easy to use, simply plug the capsule into one end and the output stage The A89U is an ideal solution when using the VP89 microphone and space is an issue.cm).The adapter is easy to use, simply plug the capsule into one end and the output stage into the other.The A89U is an ideal solution ideal when using the VP89 microphone and space is an issue..PZA MORE SPECS