Product Contents: 30mm x 8 pieces 3 sets of the above Total: 24 pieces Size: φ30 (for 30mm) Inner diameter 16mm, Outer diameter 25mm, Thickness 0.5mm These are silent silicone flat washers for arcade sticks. They are used by attaching them to the buttons of an arcade stick. By attaching them, you can reduce noise and shorten the button stroke. Since they are thin at 0.5mm, you can adjust the stroke to some extent by stacking multiple washers. Please note that interference may occur with some buttons, requiring modification of the parts. Although they are new and unused, they may have minor scratches. They will be shipped stacked in the state shown in the second photo (3 pieces stacked). Additional washers are available for both sizes at 100 yen for 3 pieces. Please comment with the size and number of sets you would like to add.