Really need help with gas caps !

[AlxxNova]

I'm just finishing up painting a set of tanks that use bolt in non-locking gas caps. The caps are from CCI and came packaged as a vented/non-vented set. Only there are no markings to show which cap is which. The first cap has four round humps that fit into the grooves in the mounting ring. The second has the same four humps but also has two notches that will not let it fit in the first ones mounting ring. So I'm assuming the second (with the two notches) is the non vented cap. If anyone is familiar with these and which is which let me know. I'd hate to ruin a paint job or start a fire by using the vented cap on the left side tank.

Any help would be much appreciated,
Alex

 

[tooter]

vent goes on right side vent has a spring in it to on top it should have a small hole in it