Check the listing for details. Alpine KTX-H12 12" Linkable Subwoofer Accessory. Condition: New. Listed at 89.95 USD. What's in the boxFront port-link Two 9" front port braces 23.25" Rear link-plate Four 25mm hex-socket screws Eight 14mm hex-socket screws Four 20mm threaded alignment posts 3mm Allen-key Installation instructions Safety warnings About this itemWritten by Crutchfield's Bob BihlmayerWhen it comes to bass, two is always better than one. Alpine's KTX-H12 linking kit allows you to connect two Alpine S-SB12V or R-SB12V 12" subwoofer enclosures to double your bass. The kit includes heavy-duty steel front and rear linking brackets to securely connect the enclosures as well as all the hardware you'll need. The front bracket's silver finish is made to coordinate with the enclosures' design, while the silver Alpine badge adds a touch of style. Warranty: 1 year.