A: Look: the inferior buckle surface looks rugged, and there will be particles. The quality board looks very flat and the panel is softer.
B, smell: the lighter with a lighter plate of the corner, 30 seconds will be charred, and the smell of plastic scorched scorch, roller anti-oil stains even if the burning of yellow hair will not have irritating smell.
C, touch: the temperature of the plastic sheet is the temperature of the plastic, so it is relatively high, to warm a little, roll the temperature of the board is the metal temperature, to cool a little.
D, listen: hand cover the corner of the panel, gently knock on the central panel, the film board sound boring a little, rolling the sound of the board crisp.