This cap fits over the barb outlet on regulators and VIPR cylinders.  This barb cap has been redesigned with ribs to prevent the installation of a cannula without first removing this outlet cover.  We have these hose barb covers available in three different colors.  Green - ACM 446;  Red - ACM 416; and Black - ACM 204.  We have a red, non-vented cap with smooth sides that can be used for other things as well.  The part number is ACM 345 NV.  We have a black non-ribbed and vented hose barb cover (Part number ACM 203).  We also have matching DISS Connection Caps for the red and green hose barb caps.

(Prevent this from happening with our patented hose barb cover with ribs.  The cannula cannot be placed over this cover without removing it.)