Thingiverse
NATO 40mm Gas-mask restrictor cap for altitude training - 4mm Hole by pieman3000
by Thingiverse
Last crawled date: 4 years, 6 months ago
This is a cap which will fit any gas-mask with a standard 40mm NATO thread including S10, FM-12, Israeli civilian etc and thus allows you to use it as an inexpensive altitude training mask. The cap comes as standard with a single 4mm hole but you could adjust this is CAD to suit your requirements