We’re building a mash tun, I only paid attention to getting a lead free flexible water connector.
I didn’t pay attention to whether it was stainless, its a polymer braided flexible connector.
The braid you want to look for is Lasco brand (part number 10-0121 or 10-0321). I get it from my local hardware store, but Amazon also carries it I have used the same braid for 20 years and over 500 batches.
I used the braid from a 1/4" ice maker supply line. I think its about 5 or 6 feet long and I have it coiled up and wired together to generally cover most of the bottom of my tun.
What is this “clean” word you mention? :) Seriously, all I do is spray all the gunk out of the cooler and then shoot water backwards up the hose and out the braid. That usually takes care of all the cleaning.