Scuba Diving Accessory: Mask Purge Valve
A purge valve can help you avoid having to tilt back your head and lifting off the mask to purge it. Instead, usually fitted in the nose piece, it allows you to exhale and purge through the one way valve.
These are standard purge valves that can be used as replacements or can be fitted to an existing mask (please check that your mask is compatible before you start cutting into it!).
Just like to reply and say thanks for the astonishing service you have
provided, this courtesy e-mail is the icing on the cake. Rest assured
you'll have my business again and both my dive buddies are now perusing the
catalogue you sent, for a stamp of their own.
Good luck for the future.