Walk-behind outdoor power equipment device, comprising a handle height adjustment assembly for adjusting a height of at least one handle member of the walk-behind outdoor power equipment device, the handle height adjustment assembly comprising: a knob assembly movable along a first axis to shift between a locked state and an unlocked state, the knob assembly being movable linearly in a direction perpendicular to the first axis to alternately enable and prevent rotation of the at least one handle member about a second axis that extends substantially parallel to the first axis, the at least one handle member rotating about the second axis to shift between a first operating position, a second operating position, and a folded position in the unlocked state, wherein the handle height adjustment assembly is configured to enable the at least one handle member to be fixed in at least the first operating position or the second operating position responsive to the handle height adjustment assembly being in the locked state, each operating position defining different handle heights for the at least one handle member, and wherein the handle height adjustment assembly is configured to enable the at least one handle member to be rotated between the first operating position, the second operating position, and the folded position responsive to the handle height adjustment assembly being in the unlocked state, the handle height adjustment assembly further comprising a handle bracket corresponding to the at least one handle member, the handle bracket being operably coupled to a blade housing of the device, wherein the knob assembly comprises a knob releasably engaged with a fastening element to alternately shift the handle height adjustment assembly between the locked and unlocked states based on a position of the fastening element, wherein the fastening element is movable within a locking slot provided in the handle bracket responsive to the handle height adjustment assembly being in the unlocked state, wherein a proximal end of the at least one handle member comprises a first engagement slot and a second engagement slot, the fastening element being insertable into the first engagement slot to be locked in the first operating position, and being insertable into the second engagement slot to be locked in the second operating position. a knob assembly movable along a first axis to shift between a locked state and an unlocked state, the knob assembly being movable linearly in a direction perpendicular to the first axis to alternately enable and prevent rotation of the at least one handle member about a second axis that extends substantially parallel to the first axis, the at least one handle member rotating about the second axis to shift between a first operating position, a second operating position, and a folded position in the unlocked state, wherein the handle height adjustment assembly is configured to enable the at least one handle member to be fixed in at least the first operating position or the second operating position responsive to the handle height adjustment assembly being in the locked state, each operating position defining different handle heights for the at least one handle member, and wherein the handle height adjustment assembly is configured to enable the at least one handle member to be rotated between the first operating position, the second operating position, and the folded position responsive to the handle height adjustment assembly being in the unlocked state, the handle height adjustment assembly further comprising a handle bracket corresponding to the at least one handle member, the handle bracket being operably coupled to a blade housing of the device, wherein the knob assembly comprises a knob releasably engaged with a fastening element to alternately shift the handle height adjustment assembly between the locked and unlocked states based on a position of the fastening element, wherein the fastening element is movable within a locking slot provided in the handle bracket responsive to the handle height adjustment assembly being in the unlocked state, wherein a proximal end of the at least one handle member comprises a first engagement slot and a second engagement slot, the fastening element being insertable into the first engagement slot to be locked in the first operating position, and being insertable into the second engagement slot to be locked in the second operating position.