Excalibur Crossbow Air Brakes for Matrix and Micro. Tests show an eight-decibel reduction in noise without reduction in arrow speed. The kit comes complete with bars pads and mounting hardware installation takes only minutes. Features of Excalibur Crossbow Air Brakes: Sound Suppression System Greatly reduces recoil energy and noise The kit comes complete with bars pads and mounting hardware installation takes only minutes For Micro and Matrix model crossbows String will need to be removed to install the kit Package Contents: Excalibur Crossbow Air Brakes Constructed of a lightweight ultra-modern energy absorbing compound. Reduces recoil energy and noise from Excalibur Micro and Matrix series crossbows.