Let's see who can guess what this is...

[ObKrieger]

Without sounding like I am totally clueless... what is the difference exactly? Were they for different situations? Which was more commonly used?

[Eric Zentner]

It is the same thing all in all .But the old school people call it,, and the correct term IMO is Small Box Respirator Face Mask Relic.
It has a hose........on it.
Eric

[ObKrieger]

Thanks! I don't even know how I could display the poor thing...

[GasMasksUK]

Once upon a time it would have looked like the one in the bottom photo posted by Eric, however almost 100 years later the effects of time and poor storage show quite clearly. You can pick up far nicer ones in the US quite easily and for reasonable prices too as they are by far the most common type of First World War respirator. I'm not too sure how would be best to display it, as the rubber perished and fused the facepiece together?

Thanks

Danny