To rip a rod with the same feeling as in the case obtained by gripping an actual grip portion, by providing a variable outer diameter rod for gripping.

A size of handrail to be purchased is determined as described below. That is, a sheet portion at the outer periphery portion of a variable outer diameter rod 1 is gripped by one hand, a sheet portion at the inner peripheral portion is gripped by another hand, and the variable outer diameter rod 1 is squeezed. In this way, the diameter of the outer periphery of the variable outer diameter rod 1 is decreased and becomes a thinner rod. Then, if this variable outer diameter rod 1 is gripped as a user grip a handrail, then the gripping force is loosened if it is too thin, and the diameter of the variable outer diameter rod 1 is gradually increased by its elastic restoring force, and whether the size is adequate for easy gripping is judged at each time. In this repeating process, a size the best fitted for gripping by the user can be found. Thus, the best gripping size can be selected by finding a same feeling that can be obtained when gripping the actual handrail or the like.