OO MAGNETIC PIVOTING SQUARE CHUNK COUPLINGS Non-polarized Standard gap between rolling stock 5 pair to plug in to NEM pockets. These are 11.5mm + 11.5mm NEM to NEM There is no A & B end will work which any way round you place your rolling stock / locos guaranteed mating no fuss. Fully compatible with all Porterhouse MODELS Couplings. Postage included in the price.