The respirator facepiece is composed of soft silicone and the headstraps are a woven nylon with elastic. The Honeywell North 7700 comes in 3 sizes (S, M, L). The North 7700 can convert to a PAPR or supplied air respirator with optional attachments.
The North 7700 is a NIOSH approved respirator in a variety of configurations. Their PAPR attachment is the North Compact Air.
Use in healthcare & for COVID
The Texas Center for Infectious Disease (TCID), which specializes in tuberculosis, has been using elastomeric respirators since 1996 and has had no employees test positive for TB since. The North 7700 is the elastomeric respirator of choice at the TCID, with 134 of 138 employees using it.
During the COVID-19 pandemic, the North 7700 has become a popular elastomeric respirator for usage in hospitals. The North 7700 can be frequently spotted in news stories featuring photos of COVID ICUs.
Like most elastomeric respirators, the Honeywell North 7700 feature a one-way exhalation valve. While the US CDC considers exhalation valves on N95s to be acceptable for source control (as of April, 2021; see NIOSH study as well as this presentation on elastomeric respirators - 19:15, 40:00 marks), some may choose to cover the exhalation valve of the respirator with e.g. a surgical mask.
A list of "DIY" exhalation valve filters (not vetted!), some from 3D printing websites: