Free Express Shipping! Yamaha Wheel Kit for DXS-Series Subwoofers (4-Casters) For DXS18, DXS15mkII, and DXS15, For DXS12mkII and DXS12 Subwoofers, Radial Ball Bearing for Smooth Operation, Includes 4 x 3" Casters, 4 x Protection Sheets, Hex Key Included