These items were added to the game alongside the original Limbus event in the October 2005 Version Update.
They are obtained from Armoury Crates that appear after defeating a particular monster on each floor of the four Apollyon areas. They can also be received as a random reward from the Gobbie Mystery Box Special Dial, or similar sources such as the Aurum Coffer or the Dial Key #ANV. In 2013 and 2014 they appeared as reward options for Repeat Login Campaign No. 6 and Repeat Login Campaign No. 11, but haven't reappeared there since.
Since the September 2011 Version Update, they have been deliverable between characters on the same account. They are all 
but, since the December 2013 Version Update, no longer 
- which also removed the option to trade these items to gain Daily Tally from the Gobbie Mystery Box. Also since losing the tag, these items have become stackable in 12s.
Artifact Armor Upgrade[]
The original purpose for these 20 items were as part of the requirements for the upgrade of Artifact Armor to Artifact Armor +1. Each item is keyed to one of the first 20 jobs (this upgrade process doesn't apply to the Seekers of Adoulin jobs Rune Fencer and Geomancer) and is combined with an equivalent Temenos Upgrade Item, a crafted material, the original piece of Artifact Armor, and a quantity of Ancient Beastcoins in a trade to Sagheera in Port Jeuno.
Upgrade Requirements[]
Biotech Armor Upgrade[]
A secondary purpose for these items was added in the June 2012 Version Update. Any different two of these 20 items can be traded along with an Arch-Omega Body Part to gain the respective piece from the Murzim Corazza Set, as below.
All items (20)