The Pyle PSi21 Recoil Stabilizer Acoustic Sound Isolation Platform helps achieve optimal audio performance. The lab-tested and scientifically engineered foam isolator pad eliminates unwanted levels of resonance and helps promote the flow of 'clean' speaker sound projection from your speaker. Stabilization, isolation and absorption gives your audio frequencies free-flow ability with deeper and more natural bass clarity. Simply place your speaker on top of the acoustic stabilizer and fill the area with more accurate and crisp sound. Unlock true audiophile performance with the Pyle PSi21 Recoil Stabilizer Foam Isolation Platform. Sold as single unit.