Machined from a solid piece of acetal for maximum reliability, it has a thick acrylic window, front aluminum bezel, and stainless steel top cover.
Depending on the type of steel, this could vary quite a bit on the galvanic index, with some being almost noble in nature, and some being almost as bad as mixing in aluminum. So I looked a bit more, and it seems that Koolance uses stainless steel in the RP-401X2 res as well. Does anyone know what grade of steel is used here? Has anyone out there used one of these in a loop with the typical nickel, copper, or brass metals in the loop? Just looking to avoid damaging something here.