Incandescent Gate Lights were invented as a extra warning to go along with 8" and 12" lights.

The 1st type of Incandescent Gate Lights were called swivel gate lights beacuse the way they were mounted on the gate. Then, 4" Gate Lights came around and were and still are the most common gate light. Next, 4" started being replaced with 7" Gate Lights, which were very popular on ATSF and still can be found in some places on Ex-ATSF trackage. The 7" Gate Lights then were being replaced with the current RECO and Aurora LED Gate Lights, since there are no LED's made for 7" Gate Lights.

7" gate lights have a huge fan following with signalfans due to their large size and rarity.