You can get them from Coralvue here:
EasyConnect 25 adapter for EasyBooster and EasySPS EVO 250ml bags
www.coralvue.com
Or you can DIY it...
I took a 1" piece of 3/8" silicone hose (perfect tight fit to the bag connector - it pushes inside)
and pushed a piece of 1/4 rigid RO tube into that (also a perfect tight fit)
and pushed the whole thing into the bag connector.
If I was to do it again I would also add a 1/4 RO shut off valve to the RO line so I can turn it off if needed to disconnect for some reason. If you want pics let me know and I'll take some tonight.
HTH