Chasons Music
Dave Chamberlain
102 Shasta Street
Chula Vista, CA 91910  USA
619-742-8787
seafarer@cox.net
dave@chasonsmusic.com
chasonsmusic.com
octobrass.com

The pressure hole is closed.  Sliding the brass sleeve opens the hole which releases pressure and allows you to match the resistance you experience with your horn.