Saddle drafting chairs have basically two features that set them apart from the rest, they are designed a little higher than regular saddle rolling chairs and a footrest is added.
The first has to do with their focused use in drafting or other high work surfaces. The second with the need of support of your feet since they not in direct contact with the floor but suspended by the height of the chair so the footrest helps as support point.
Some feet supports are fixed to the 5-leg base of the chair and others can be adjusted to a specific height. This can be done thanks to a rotative knob that is in contact with the hydraulic cylinder. So you can adjust it as high or as down until you find the most ergonomic distance.
Check out these great options for saddle drafting chairs
