ABEC 7 bearings would be very fast and smooth, the price will be higher.

Here Are skate bearing procesion ,from low to high for your reference.

• ABEC 1 equal to ISO P0
• ABEC 3 equal to ISO P6
• ABEC 5 equal to ISO P5
• ABEC 7 equal to ISO P4
• ABEC 9 equal to ISO P2

There are a number of factors covered by the abec bearings grades, but to give you an idea we will just examine one of these factors-the eccentricity (out of roundness) of the track in the inner ring. For an ABEC 1 (lowest grade ) bearing, the maximum eccentricity allowable is 0.0075 mm (0.000295"). This is quite precise-more than precise enough for skates and skateboards. The figures for other grades are:

ABEC3: 0.005 mm (0.000197")

ABEC5: 0.0035 mm (0.000138")

ABEC7: 0.0025 mm (0.000098")

ABEC9: 0.0012 mm (0.000047")

MKL BEARINGS is Skateboard Bearing Wholesale Suppliers ,we can produce different grade skate roller bearings for you .