I have not put them in my loop yet, but I have full confidence that they would retain the water no problem. They have one o-ring for the G 1'4" thread and two on the compression end to keep a good seal. They were way way way cheaper than the competition like EK and corsair, and look like they will be just as quality. They look very similar to bitspower fittings, but maybe a tad smaller. Either way these black fittings will look great in my build.
I ordered quite a big batch of different Barrow stuff and I was positively surprised how good quality was throughout all the products. This order being my first touch with Barrow products. I have to give credits to seller for having EXCELLENT communications & service, especially being able to modify delivery as per your wishes and everything went super smooth. Goods arrived fast and proper documents were delivered for duty. Big thumbs up, will most def order again!