A gate all around transistor may be improved to provide better transistor circuits performance. In one example, a transistor circuit may include a dielectric or air gap as an insulator between the channels of the transistors in the circuit. In another example, a transistor may include a first channel surrounded by a first metal, a second channel surrounded by a second metal proximate to the first channel, and an insulator, such as a dielectric or air gap, between the first metal and the second metal. The insulator helps reduce the parasitic capacitance between the source/drain regions and the metal fill regions of the transistor.