The camshaft's lift determines the distance between the valve and the valve seat (i.e. how far open the valve is). The farther the valve rises from its seat the more airflow can be provided, thus increasing the power produced. Higher valve lift can have the same effect of increasing peak power as increased duration, without the downsides caused by increased valve overlap. Most overhead valve engines have a rocker ratio of greater than one, therefore the distance that the valve opens (the "valve lift") is greater than the distance from the peak of the camshaft's lobe to the base circle (the "camshaft lift").