This is a replacement 3000psi burst disc for for the All in One Mini Regulator.

If you leave a cylinder connected then put that cylinder in a hot car or hot garage the temperatures are likely to exceed safe working pressures for the All in One Mini Regulator.  If you are in this position you migh hear the burst disk blow on your All In One Mini Regulator meaning you will have to replace it with this spare part.

Simple unscrew the old one with a shifter and screw in this new one.