There's a source control version of the Eclipse with no exhalation valve. One could also just cover the exhalation valve with either something impermeable or the electrostatic filtration layer scavenged from a medical mask or respirator if needed.
Other elastomerics that are popular these days:
MSA Advantage (speech diaphragm, with source control)
3M Secure Click (speech diaphragm, great feature where it auto-seal checks for you, no source control)
Honeywell RU8500 (speech diaphragm, no source control)
FloMask (low profile, good speech audibility, source control)
There's a source control version of the Eclipse with no exhalation valve. One could also just cover the exhalation valve with either something impermeable or the electrostatic filtration layer scavenged from a medical mask or respirator if needed.
Other elastomerics that are popular these days:
MSA Advantage (speech diaphragm, with source control)
3M Secure Click (speech diaphragm, great feature where it auto-seal checks for you, no source control)
Honeywell RU8500 (speech diaphragm, no source control)
FloMask (low profile, good speech audibility, source control)
EnvoMask (low profile, source control)