Yep - that is a bearing lock nut.
A slotted hex nut has slots cut into each face to permit a split pin to lock the nut to prevent movement. A castle nut is similar but the area where the slots are is turned to a smaller diameter. This generally provides better thread engagement of the nut and also allows the eye of the split pin to sit closer to the shaft.
A slotted hex nut has slots cut into each face to permit a split pin to lock the nut to prevent movement. A castle nut is similar but the area where the slots are is turned to a smaller diameter. This generally provides better thread engagement of the nut and also allows the eye of the split pin to sit closer to the shaft.
Hunting American dentists since 2015.