All of our Cooling Plates are made from 304-type stainless steel.  All units features weld-less type fittings on the shanks.  To install in a tank you drill, and then punch out, a hole in your variable volume lid or in the top of your sealed tank and the cooling plate fits into place and cinches up with included gaskets to make an airtight seal.  Of course you can still use the cooling plates in a macro bin or any other open tank without doing a hard install.