Straight keys, also called parallel or Form-B machine keys, feature straight and parallel sides set 90° from each other. This design creates a large contact area between the key, the shaft, and the rotating component. This ensures efficient force transfer and reduces the chance of the key deforming or slipping.

Round keys, also called feather keys or Form-A keys, feature rounded ends rather than the straight cuts of regular keys. These rounded ends fit exactly into milled channels and transfer more force with less friction than straight keys.

Gib head keys are tapered straight keys with a notched head for hammering into place and removal. This head serves as a striking point to reduce damage to the shaft and provides a levering point to remove the key. Their length and height measurements do not include the head as the head never enters the keyway.

Key assortments contain sets of various sizes of machine keys. They are ideal for high-volume environments where the same keys are used repeatedly such as repair shops and production areas.