TASTER PACK OO MAGNETIC PIVOTING Non-polarized to plug in to NEM pockets. There is 9.5mm + 9.5mm NEM to NEM one pair. There is 9.5mm + 9.5mm PIVOTING NEM to NEM one pair. There is 11.5mm + 11.5mm PIVOTING NEM to NEM one pair. There is 13.5mm + 13.5mm PIVOTING NEM to NEM one pair. There is no A & B end will work which any way round you place your rolling stock / locos. Fully compatible with all Porterhouse MODELS Couplings.