It looks like this Part has been superseded by LEGO Part 4070 Brick Special 1 x 1 with Headlight and No Slot.
We keep these variations to help maintain 'correct' inventories.
Click on a colored part below to see the Sets and MOCs that use part 4070a Brick Special 1 x 1 with Headlight and Slot in that color. You can find an overview of all LEGO Colors here.
If a color is missing, it probably needs to be added to a Set Inventory.
This part has been used by MOCs in the following colors but not officially released.