When sourcing multi-function pens, you must evaluate the integration of tools such as stylus tips, LED lights, spirit levels, rulers (metric and imperial), and screwdrivers (flathead and Phillips). Ensure the barrel material is made of high-grade aluminum or stainless steel for durability, as plastic alternatives often fail under the torque of the screwdriver function. The ink cartridge should be a standard D1 size to ensure end-users can easily find replacements, maintaining the product's long-term utility.