Methods and apparatus are provided for an achieving low-rate collagen shrinkage using an electrode array comprising an elongated insulator strip having at least one pair of spaced-apart bi-polar RF electrodes, and a channeling disposed on the strip between the bi-polar electrodes to direct the flow of RF current therebetween. The optical film comprises a cellulose ester resin having high stretching adequacy and having an average acetyl group substitution degree of 2. The element has particular use in a wrist axis of a painting robot. Then, the controller deletes the content data stored in the memory. At this position, a user can easily pull the handle assembly up to its maximum.