When sourcing tube expanders, you must prioritize material compatibility and expansion range. Ensure the tool is suitable for the specific metal you are working with, such as copper, aluminum, titanium, or stainless steel, as hardness levels vary. Look for hardened alloy steel construction in the expansion head to ensure durability. For HVAC or plumbing applications, verify the supported tube diameters (typically ranging from 3/8" to 1-1/8" or metric equivalents) and ensure the tool provides a uniform, 360-degree expansion to prevent tube splitting or uneven wall thinning.