DescriptionThis set of grinding wheels is for electric drills. They are twice as much harder than red-cover ones. We designed and manufactured it with the purpose of long time of using. With its extraordinary durability, this product could be serving you well for a long time to come.Features-Color: Blue. -Material:Aluminium oxide -Size: 4.7x0.6x0.6cm/ 1.85x0.23x0.23inches. -Specification:(3mm, 4mm, 5mm, 6mm, 8mm Cone Shape) x 10 -This set of grinding wheels is for electric drills. -They are twice as much harder than red-cover ones. -Compatible with most devices. -We designed and manufactured it with the purpose of long time of using. -With its extraordinary durability, this product could be serving you well for a long time to come.