Outside diameter: 19 mm
Original part for YoYoFactory Yo-yos: the white response pads make your YoYoFactory Yo-Yo play smooth on the string, and come back to your hand when you want it to. They are designed to last long.
The adhesive backing allows you to set them up very easily, after removing the "old" pads. Your yo-yo will be glad;-)
Response pads are sold in pairs.