The 1980 train catalog and ideas book (7777) enticed Lego fans with nighttime dioramas featuring lampposts and lights inside the trains. Even though light bricks of the same size were available in both 12-volt and 4.5-volt guise, the train headlight/taillight (using unique prisms and holder bricks) and lamppost sets were normally only available with the expensive 12-volt light bricks included. Making these theoretically universal features available only as 12-volt items served to further elevate the 12-volt system away from the more limited 4.5-volt system.