O ring help

[TristanG.Arellano]

Help please, I’m new to water cooling and just bought everything I knew I would need, pump,  reservoir, Cpu block, radiator, tubing and just got my fittings theyre monsoon free center compression fittings for flex tubing and they came with two sets of O rings all I know is that one set is UV reactive and the other is a back up. Do I put the o rings on the barb end or the g1/4 end.

[airdeano]

g 1/4 end. this seals the fitting to the object it is installed in.