There are two styles of knobs here, and I will add more as I come across them. 
The first style will fit Harbor Freight 20 Ton Bottle Jacks, and probably others, but no guarantee is given.  There is a hole in the design that will need to be final-drilled for the size of pin or roll-pin used to mount the knob.
The second style fits bottle jacks with a double-D type of release. It may fit multiple makes/models of jacks, but no guarantee is given. There is a hole in the design that can be drilled/tapped to add a set-screw to help hold the knob on the jack if so desired.