See "220V Cooling Fan" motor silicon steel thickness: silicon steel merits of the test more difficult, the use of different materials the effect is not the same, however, as a consumer to identify the easiest way is to look at the thickness of the silicon steel. Under the theory, the same "220V Cooling Fan" silicon steel material, the thickness of the bigger motor, the better, but the cost is higher. "220V Cooling Fan" motor silicon steel specifications vary by product category is different, in general, there is 13mm (26 fold), 14mm (28 fold), 16mm (32 fold), 18mm (36 fold), 22mm (48 fold), etc. . Generally used for 13mm ~ 16mm fan page, 18mm more than for stand fan.