The Reinforcement Expansion is an item added in the August 10th 2015 update along with the Summer Event. Having the item allows you to reinforce a ship to permanently add an additional consumable equipment slot. The reinforcement will remain after a remodel. This means you can equip a ship with valuable equipment like Damecons without compromising the main equipment. Currently, the Reinforcement Expansion is available as an event map reward, as a quest reward from B90 , B103 and B104 or through the Shop for 500 DMM points.