The 12 V Car Adapter for the Spectrum Two N comes standard in the Spectrum Two N Portability Pack (L1600238). Its dimensions are 160 (W) x 72 (H) x 29 (D) mm, and it weighs 325 g.
The Car Adapter is a required component of the Portable Battery Pack for the Spectrum Two N (L1600233), but can be ordered separately as a replacement or spare using this part number.