SDS Stainless Steel Stabilizer Attachment for SDS iMount 2.0 Aluminum Mini Keyboard Shelf SDS VESA Mount Keyboard Tray bolt-on Stiffener Plate ONLY For The MINI Reduces Bounce makes the SDS aluminum tray more rigid Stainless Steel Bolt on Stiffener plate Recommended for use when tray is arm mounted. Not require if tray is mounted directly to wall