Hello, I changed my beer line and when disassembling the shank, etc. on my tower, I notice that there is a brass-like discoloration within. Pics below may not show this well, also, I didn't take a pic, but the tail piece has this color too when you look close. My question is: Is there any way to determine if this is stainless steel or not? I can't find this in the specs on the original system where I purchased it all. I'm still researching this sort of thing, maybe it's not all that important, but it seems that it's recommended to try and stay with Stainless Steel parts whenever possible? So, I may change these out. Thanks!