Go to the Inventory page. On the left side, right below Simple and Configurable tabs you will find a light blue button called Filter.
You can begin filtering your Inventory items by pressing on that button and selecting your Filter Type.
Press on your selected filter, for this example I've chosen Product SKU. I can now choose weather I want to find Inventory items with SKU's that either include or exclude specific text or numbers.
In this case I have chosen to sort out all Inventory items who's SKU include the word "PEN".
All I need to do now is press Add and wait for the orders to sort out.
From here, if I want to, I can add more filters. In this case I will choose that all inventory items would be further filtered to show only those that contain the STOP Tag as well.
We can now see only those inventory items that fall under both Filter rules.
If I decide that this combination of Filters I plan to use multiple times in the future, I can click Save near the end of the displayed filter.
This will open a pop-up window allowing me to save this filter set for future use.
We can now go into Filters and Instead of Add a new filter, we can now press on the Saved Filters and choose from the list of our saved options and press Apply.
Quick Note on the filter types:
Price: filter by price less, greater or equal to the orders total.
Quantity: filter by quantity less, greater or equal to the available stock.
Store: filter our orders from specific Sales Channel.
Supplier: filter our orders containing items from a specific Supplier.
Product Name: include or exclude orders containing a specific Inventory item.
Product SKU: include or exclude orders containing a specific SKU.
Category: filter our items that belong to a specific category.
Tag: include or exclude orders containing a specific Tag.
FBA Quantity: filter by quantity less, greater or equal to the available FBA stock.