When sourcing a tube bender kit, you must prioritize material compatibility and bending precision. Ensure the kit supports common materials like soft copper, aluminum, and thin-walled stainless steel. Look for a bending range of 0 to 180 degrees with clear, laser-etched scale marks to prevent over-bending. The kit should include multiple interchangeable mandrels or formers (typically ranging from 1/4" to 7/8" or 6mm to 22mm) made of heavy-duty aluminum alloy or hardened steel to prevent deformation during high-pressure tasks.