1. You can access the Selection List, where you can use the Quick Select feature to filter items on the list
2. You can right click on the Product Field for advanced searches and selections
3. Or, you can type in the first few characters of the item reference number or the item's description, which will automatically filter your Selection List.
Let's take a closer look at the last option #3 which has been enhanced in Sage X3 Version 6.5 ...
Getting Started with Sage X3 Product Search
Typing in the first few characters of the item reference number will filter your Selection List to those products that have an item reference number starting with the same characters.