The ones now in there have aluminum base and I replaced one yesterday and now see another one is out. I put these all in at once and it appears they are going out within days of each other. This is why I have to have lots of these bulbs. Maybe the new GE ones have a bass bottom since it says they last 2 and 1/2 times longer than others.
I worked for 2 distributors who sold them. They were good people to deal with.
They also sold bulbs in bulk 24 packs for maintenance people. Were not individually packaged but cheaper.