Adjustable Speed Control, 1/4 NPT, 2.19 Inch Long

That's exactly what it's for. This speed control is designed to manage airflow from the exhaust ports of air valves.

Exhaust flow control is exactly what this unit handles. It threads into the exhaust port of an air valve using a 1/4 NPT connection and uses an adjustment screw to dial in how much air gets out, which in turn governs how fast your actuator moves. The lock nut holds your setting in place once you get it where you want it. Sintered bronze construction on the flow element helps keep things clean while still letting air pass at a controlled rate.