Quantity  20 piece(s) per pack  Color  Black   Material  Ferrite magnet   Specification  Diameter: 20mm; Thickness: 1.5mm; This ferrite magnet ring is used for electricity meter， instrument， electric motor， automatic control， microwave device， radar， medical apparatus and instruments etc.   Packing List  20 x Ferrite magnets<img src="http://112.74.112.28/down/products/423803/423803_000.jpg">