These are pieces of the MagmaBore which is the end game (for Frozen Factory) machine that gates the destruction of the CryoPlasm Spawners. It requires a large investment of raw/refined resources and power. The components are built in lots of 99 in order to facilitate not having to click as many times to fabricate the parts.
See Also MagmaBore.
(Requires blocks 3267 total for the completed machine, or 33 fabrications.)
Unlocked by MagmaBore(Research).