This miniature valve manufactured by Lee comes with 3 ports that are designed to facilitate fluid flow to a common outlet, from one of the two available inlet sources. Because of the reduced size of the valve, it is unlikely that you will experience any problem while fitting them into the head of an actuator.
In terms of the inserts proposed by Lee, there is no requirement for elastomeric seals or O-rings. Choose one of the four sizes available, each with a diameter between 0.187mm and 0.5mm.