What it is printed in.
Printed entirely in PLA, a plastic made from plant sugars - from crops such as corn - instead of oil.
The parts that glow are translucent PLA, two beads thick; the bases, backplates, rings, bands and tops are matte PLA.
A printed lamp is not made for heat. That is why every lamp ships with an LED bulb, why no other kind should ever go in it, and why a lamp should not sit in hot direct sun.
Each spool varies very slightly in tint, so two lamps bought months apart may not match exactly. For lamps that must match, order them together.