Amazon.com: Alpine (2) X-W10D4 Car Audio Type X Series Sub 1800W Peak 10" Subwoofer Bundle with Harmony HA-A1500.1 Amplifier & Amp Kit : Electronics
Custom Ported Sub Box Enclosure for 1 12" Alpine Type X Subwoofer ~ X-Series | eBay
Disassembly of an Alpine Type-X SWX-1243D (will post more as I get deeper) : r/CarAV
Alpine X-W12D4 | Performance Car Audio Visual
Alpine SWX-1043D Type-X 10" subwoofer with dual 4-ohm voice coils at Crutchfield
Alpine SWX-1043D Type-X 10" DVC Subwoofer - Signature Car Sound
Amazon.com: Alpine Bundle Compatible with Universal Car X-W12D4 Type X 12" Loaded SPL Bass Subwoofer Labyrinth Vent Sub Box Stereo Enclosure : Electronics