... . of gear module HSN:Inner gear, single-row ball A:bigger module, without A:normal(2)--Dia. of track center, mm (3)Single ... Classification code No.of gear module A:Both rings with installation bolt holes A:bigger module, without, A:normal B:Both rings with installation ... screw holes, inner ring with installation bolt holes High precision, without G:normal D:Outer ring with installation bolt holes, inner ...