The ST53 combines Avon Protection's FM53 mask technology with an advanced modular breathing apparatus to provide positive pressure SCBA and/or PAPR capability for specialist operations.
 
Developed with the unknown elements of a threat scenario in mind, the ST53™ is the most advanced CBRN respiratory solution on the market.  It enables a fast response to changing operational conditions in one complete modular system.
 
A switch between negative (filter) and positive (SCBA) pressure is achieved at the flick of a lever on the front of the mask. And by attaching a short or long duration compressed air cylinder, it is possible to enter a location on filter mode, assess the situation and change to SCBA mode if the need arises.