This is an extra standard NATO 40mm x 1/7” DIN 3283 filter port plug supplied with the MESTEL SGE150, SGE400 masks.
It will fit and plug any NATO 40mm x 1/7” filter port in any mask model from any mask manufacturer.
How to use:
If your mask has more than one filter port, all filter ports have to be either plugged by the filter you are using (up to 2 filters per mask) or a filter plug to work correctly! That way only filtered air can enter the mask. Order accordingly and always keep one extra mask plug in stock in case you lose one of the original plugs. This will also enable you to look underwater with your plugged mask for a short period of time (without breathing at all) in case of emergency.