Using the new @e Selector I managed to create a method to test which Inventory Slot in the Hotbar a Player. It doesn't have a number, but you can easily put items onto the off-hand slot by pressing F as you're holding the item you want to equip. How to give a player an item in a specific slot. Minecraft displays the player inventory differently, according to how the window was opened. Ranges of slot indices vary in meaning between Player Inventory · Chest.