Bose Style Replacement Speaker, Woofer, Fits Bose 301, Bose 601, W-810 Made in the USA! New materials last much longer than the original design! Size: 8-1/4 6 ohms for compatibility with older 4 ohm models and current 8 ohm versions Fs: 38 Hz, Vas: 2.42 cu. ft., Qms: 5.9, Qes: .33, Qts: .31, Xmax: 4.3mm