Slotted nuts are hex nuts with six large slots 60° apart in the top center of each flat side. Their strength is said to be 80% of "full thickness nuts of the same size, style and grade." Slotted nuts are used with bolts and studs that have a hole drilled in their threaded section through which a cotter pin is inserted to prevent the nut from rotating. The nut is quite effectively retained until the pin is removed or shears. They are commonly used to secure the position of wheel bearings on spindles and are also called: spindle nuts. Slotted nuts may be interchanged with castle nuts, although slotted nuts have a lower profile because they do not have the cylindrical top. They are not used with lock washers.