Here are some pics of the amazingly accurate ventilator from NJ Sekela. They can be slid open and closed by a lever on the ventilator itself. They are installed on the first few caps and are being shipped out.
There are 2 caps currently available:
1 @ 7 1/4
1 @ 7 1/2
Both "Type I" LJ&I Phillips contract.
Caps are available for order immediately in both "type" styles.