From Manufacturer
The Rycote XY/MS mount is specifically designed to mount two miniature and remote microphone capsules in XY or MS stereo pickup angles. The XY/MS mount will accommodate microphones measuring 19/20mm or 21/22mm in diameter. A reference-pin location system will adjust pick up angles between 120, 105, 90, 70 and 0 degrees. The entire XY/MS mount may be installed, as an accessory into the Rycote Stereo Extended Ball Gag suspension windshield, or mounted as a stand-alone device.