There is good and bad. It's just that you can't tell just by looking at the appearance
1. Appearance should be clean and neat. The weld seams of the water tank must be regular and the structural joints must be regular.
2. The key is the welding of the inner liner, the thickness of the material, the foaming process and the density of the polyurethane insulation layer, etc. These can only be known by using it
If there is a good If it is manufactured by a manufacturer of advanced technology and equipment, it is always guaranteed