The drinking device for SGE 400 - 400/3 and 400/3BB masks is an optional extra accessory that is easily connected to the bottom drinking cap of the Mestel 400 type masks. That is if you ordered your mask with the optional extra drinking device. (factory assembled)
The Internal built-in drinking device inside your SGE 400 type mask may be rotated, moving the internal drinking tube to intercept the mouth and avoiding any uncomfortable condition when not in use for drinking.
The external squeeze tube is supplied with a safety valve. To drink from it you need to squeeze the 2 finger valve, otherwise, the tube is hermetically closed. After squeezing the valve you can suck the drink like drinking with a straw through the mask