instead of replacing the whole valve, can i buy 1 of these and just replace the o-ring?
Those O rings are designed for tap spindles, not tap valves, and might not fit correctly. There is possibly an O ring in the assorted size pack that would fit. It would be best to take the tap valve with you into a store, and a helpful team member can have a look at it for you and see if they will fit. Just so you are aware, it will probably cost a similar amount to replace the whole valve with a HydroSeal 12mm Tap Valves - 2 Pack. However, if you get a pack of O rings that fit, you'd have plenty extra to replace them in the future.
Please let me know if you need further assistance or have questions.
thanks Mitchell! i just thought i could replace the rubber ring rather than waste the metal valve. having said that, it might not be that easy to put the new o-ring in without damaging it.