Mogul Sized 3-Way Light Bulb
This is a Mogul base, 3 Way Soft White bulb. It is 100/200/300 watts and is rated for 1,200 hrs. This hard-to-find bulb is the type that goes in the center socket of many vintage floor lamps like the one pictured here.
We also carry replacement Mogul Sockets: http://diylightingsupplies.com/products/3-way-mogul-porcelain-socket