The 100 series front and top reading compasses have 3 yellow lubber lines and an apparent scale size of 100mm. The two side view lubber lines at 45° offset allow easy reading and also allow for mounting the compass to one side of the steering position.
The 70 series front and top reading compasses have one main yellow lubber line that allows easy and safe reading at a glance. Apparent scale size of 70mm.
