Image Item No. Description  x871a  Electric, Train 4.5V Whistle Control Block 4 x 8 x 2 with Forward/Stop Functions Catalog: Parts: Electric, Train  x871b  Electric, Train 4.5V Whistle Control Block 4 x 8 x 2 with Forward/Stop/Reverse Functions Catalog: Parts: Electric, Train  4171  Electric, Train Light Prism 1 x 3 Catalog: Parts: Electric, Train