Check the listing for details. Primacoustic RX9 - DF Horizontal Recoil Stabilizer, 5-Degree Down-Fire. Condition: New. Listed at 184.99 USD. The Primacoustic Recoil Stabilizer (this is the RX9-DF Horizontal Recoil Stabilizer, 5-degree down-fire version) is a unique speaker mounting device that at once eliminates disruptive resonant coupling from the loudspeaker to the stand, while providing a stable base that reduces the recoil caused by the forward energy of the loudspeaker motion.Made from three basic components, the Recoil Stabilizer is essentially a platform for the loudspeaker that features a high-density urethane base that isolates the speaker from the shelf, monitor-bridge or stand. This effectively decouples the loudspeaker to eliminate vibration-borne resonance to the substructure. A heavy laser-cut steel plate is added and sandwiched between the isolation layer and a no-slip neoprene top.