I purchased a 3" bubble cap column with copper trays. My application requires stainless steel so I purchased 3" SS bubble cap trays separately to replace the copper plates in the column. The bubble caps are good, but the flat steel plates are undersized and do not fit in the 3" column I purchased. The gaskets shipped with steel trays were also not suitable. I've requested the right sized steel plates and waiting for the same.
I tested the copper bubble cap column by itself and it works great and is a great value.