This style of 2-way mux has the smallest dimensions, although not the fastest speed. For fastest speed, the output should be driven through an inverter followed by a transfer gate. However, inserting the metal wire to join the P and N transistors  of the inverters makes the cell wider (connecting <SPAN CLASS="boldred">n2</SPAN> to <SPAN CLASS="boldred">n4</SPAN> and <SPAN CLASS="boldred">n1</SPAN> to <SPAN CLASS="boldred">n3</SPAN> in the schematics below, and making sure that the transistors closest to the supply are connected to <SPAN CLASS="boldred">s</SPAN> or <SPAN CLASS="boldred">sn</SPAN>). The cells here use a P:N ratio of 2.