Internal structure and material change
C: symmetrical roller, steel plate stamping holder
MB: symmetrical roller, two pieces of copper holder
CA: symmetrical roller, integral brass cage
M: reinforced design, symmetrical roller, integral brass cage
CTN1: symmetrical roller, nylon holder
External shape change
K: tapered bore bearing, taper is 1:12
K30: tapered bore bearing, taper is 1:30
N: there is a stop on the outer ring groove
P0: equivalent to the original code G level
P6: equivalent to the original code E level
C0 group: basic clearance, code can be omitted
C2: less than the basic clearance group
C3: clearance is larger than that in group C0
C4: clearance is larger than that in group C3
C6: clearance is larger than that in group C4
C9: W33: special clearance lubricating oil tank and a lubrication hole in the outer ring of the bearing