If the ad is up, they are still available.

Seas custom 6-1/2″ 4Ω woofers based on L18RNX/P but with black anodized dustcap+cone and a low frequency optimized motor.

Great speaker for your doors or rear shelf. Made in Norway.

$50 per woofer+Hst, $99 for a pair + HST. Quad pack also available for $185 + HST. That's more than 60% off the retail price!

Specifications

Black Aluminum Cone and Dust Cap Low Loss Surround Power Handling: 100W Long Term, 250W Short Term (both as per IEC 268-5) Basket Outside Diameter = 176.0 mm Xmax = 6.0mm (12.0mm peak to peak)

Voice Coil

39mm diameter 2-layer copper wire 4 Ω nominal impedance Aluminum Former Overhung Design

Thiel/Small Parameters Free Air Resonance, Fo 29 Hz Moving Mass, Mms 22.18 g Force Factor, BL 5.4 N/A Impedance at Fo, Zo 31 Ω Voice Coil DC resistance, Rdc 3.23 Ω Effective Area, S 136 cm^2 Mech. Resonance, Rmec 1.04 Ns/m Qms 3.9 Qes 0.45 Qts 0.41 VAS 35.2 liters CMS 1.36 mm/N

Similar to Scanspeak, Eton, Focal, Morel, Audax, Vifa, Etc.

Much better than SBacoustics, Peerless, JBL, MTX, Kicker, Rockford Fosgate, JL Audio, Kenwood (all made in China)