The adustable muffler is for the ED7021 gate valve. If it gets clogged it will quit exhausting air causing the lift gate to act up. It's adjustable and exhausts the air pressure from the system out to allow the lift door to lower back down to be locked.
Adjustable to control how fast the lift gate lowers
Uses a nut and flat head set pin to adjust the exhaust pressure
Screws onto the ED7021 valve