Abstract: A tensioning mechanism for adjusting tension of a cutting chain in a chain saw. A rotatable knob operates with an engine chassis, clutch cover, and guide bar, whereby the knob may be rotated between a tightened position and loosened position, by which the guide bar is loosened and may be adjusted. The knob is provided with a knob handle, pivotally connected to the knob and pivotable between locked and unlocked positions. When the knob handle is in the locked position, at least one, but not all, of a plurality of handle engagement points engage with corresponding fixed engagement points that are fixed relative to the clutch cover. When the knob handle is in the unlocked position, the handle engagement points are disengaged from the fixed engagement points. Further, the engagement points are visible when the knob handle is in both locked and unlocked positions.