Holds enough to pave over a single planet, and resupplies the ILS super-fast. If you need something even more robust, give the MK2 version a try!
Part of the "Fetchingly Fast Furnishment for Blueprint Barons" post and collection. Basic idea is to have a factory that not only makes the things at a good clip, but refills the ILS with replacements super fast to cut down on the wait time when you're slamming down blueprints left and right.