PEPPERLONELY Brand 100 Sets Aluminum Tone Shank Wire Back Cover Metal Buttons Quantity: 100 Sets Size: 19mmx19mm(6/8"x6/8") 17mmx17mm (5/8"x 5/8") Hole size: 3.8mmx3.3mm( 1/8"x 1/8") Thickness: 4.4mm 7mm( 1/8")( 2/8") Material: Aluminum(Cadmium Safe)