12" Genuine Acoustic Research Woofer, AR3a, AR9, Others, 12100032 12" Genuine Acoustic Research Woofer, AR3a, AR9, Others, 12100032 Special 12" truncated frame Original Acoustic Research design, paper cone, poly foam surround New materials last much longer than the original design! Specs: Size: 12" (11-3/8" across flat sides), Depth: 4-1/2, Voice coil: 2"- 4 layer, Magnet: 40 oz, Impedance: 4 ohms, Re: 3.1 ohms