Narrow face flange - stepped bore
<img src="https://eng-calculations.com/SVG/EN/EN_13445-3/Narrow face flange - stepped bore.svg" alt="Narrow_face_flange_-_stepped_bore" title="Narrow_face_flange_-_stepped_bore">
https://eng-calculations.com/SVG/EN/EN_13445-3/Narrow face flange - stepped bore.svg