Review on Elevate Your Studio Recording with Electro-Voice 309A Suspension Shock Mount for RE20, RE27N/D and RE320 Microphones by Yung Kaelin

This general description or EV dimensional drawing shows that the two parts of the adapter come out of the box screwed together and appear as one piece. After unscrewing the two parts of the adapter with your finger, the set screw (winged) comes out of the adapter. You turn the adapter upside down and screw a set screw into the top of the adapter. This allows the 309A to be used with any studio arm, such as the Rode PSA 1 microphone. This is why Revain shows that, despite being two different brands, they are often ordered together and initially do not appear to be usable together.