A semiconductor device according to the present disclosure includes a first transistor and a second transistor. The first transistor includes a plurality of first channel members and a first gate structure wrapping around each of the plurality of first channel members. The second transistor includes a plurality of second channel members and a second gate structure disposed over the plurality of second channel members. Each of the plurality of first channel members has a first width and a first height smaller than the first width. Each of the plurality of second channel members has a second width and a second height greater than the second width.