Retention Point: The Single Biggest Secret to Membership and Subscription Growth for Associations, SAAS, Publishers, Digital Access, Subscription Boxes and all Membership and Subscription Businesses

Sundown Audio M18 Car Subwoofer – 18" Dual 1 Ohm, 2000W RMS/4000W Peak, 3" Aluminum VC, 35mm Xmax, Mega Roll Surround, Quad Magnet Motor, Low-Distortion SPL Sub

Rockville RSV15 15" 2.6 Cu.Ft. Vented Car Audio Subwoofer Box, 3/4" MDF, 32Hz Tuned, Gold Terminals, Black Carpet Finish, for Deep Bass in Car Audio Systems

Pyle 3000 Watts Box Subwoofer Speaker - Active Powered 18” inch Woofer, Loud Bass, with DSP Digital Signal Processor for Home Theater System, Pro DJ Sound, Pole Mount Socket and Carrying Handles

PRORECK SP-18X Active Powered PA DJ Subwoofer Cabinet 18 inch 3000W P.M.P.O with Class-D Amplifier, 3 DSP Presets-Monitor, Coil Bass Reinforcement, Black, for Wedding, Party, Concert, Church (One Sub)

Skar Audio ZVX-18v2 D1 18" 3200 Watt Max Power Dual 1 Ohm SPL Car Subwoofer

Rockville RBS15 4.4 Cu Ft Single 15" Vented Car Subwoofer Enclosure Box, SPL-Tuned, USA-Made MDF, Durable Carpet, for High-Powered Car Audio Systems

CT Sounds TROPO-18-D2 18 Inch Car Subwoofer Dual 2 Ohm, 1300 Watts Max

Skar Audio ZVX-18v2 D2 18" 3200 Watt Max Power Dual 2 Ohm SPL Car Subwoofer