The size of a reciprocating saw is primarily specified by the diameter of the blade , which determines how thick of a material can be cut. Other factors, such as motor amperage and chuck size, are relevant to performance but not size. Therefore, the blade diameter is the key measure for these tools. ;
The size of a reciprocating saw is primarily specified by the diameter of the blade, which dictates its cutting capacity. Other aspects like the amperage of the motor and size of the chuck are related to performance but not directly to size. Therefore, the correct option is B: Diameter of blade.
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