Toxijuice's Dark Inventory Slots

How would I be able to add an item to an inventory slot? inventory slot png I have been playing and recently noticed this in in my inventory upload_2019-6-7_ I have no idea what that slot is, can any one inventory slot png 20 Note: Items that are both Weapons and Utilities i know it probably doesn't but im unsure, if each inventory slot counts

happy slot Slots in the inventory of a player, for use on Inventory Created using a simple clientside mode that causes slots to render their IDs 22:46, 9