This is a medium-sized, tipped carbon filament bulb, with a Ruby Red-colored envelope (true red glass, not painted). This bulb may have been used in a darkroom lamp, for developing black & white film. The sleeve pictured belongs to a different bulb, however the original sleeve of this bulb must have looked pretty much the same, except at the time they still had many patent notices written on them with red ink. Back then, bulbs were a fairly new invention, and bulb patents were still being enforced. Lightbulb manufacturers had to make sure that you were aware of these patents by printing them all over the packaging. Patent notices were also included inside the stem of each bulb, in a little brown piece of paper. (see an original carbon bulb box that reads "Look for the license label in the stem" here
). The many lightbulb manufacturers that existed during the time had to pay royalties to license these patents so that they could manufacture lightbulbs legally. For example, I have a "Sterling" carbon bulb that has a little note in its stem that says: "The manufacturer of this lamp is licensed under patents noted on the other side". On the other side you can see lots of patents listed. Click here
to see one of these little brown notes (in some bulbs they are red). It appears that in the early 1910's, the requirement of adding little patent notes to each bulb was dropped, since I don't remember seeing a post-1910 bulb with the notes.
I got my red bulb for real cheap, but I'm sure its real market value is easily over $35.