Oh happy days, reminds me of ours when we used to live in DC, very practical, although ours developed a fault and it started to get very wet in the cupboard. Hubby (boyfriend at the time) decided that the vent tube must be blocked with fluff. So stuffed his arm up the tube to pull out the fluff, felt a blockage and yanked on it, nearly fell off his ladder when I very large dead bird came out. No problems with damp after that.
Anyway I digress I think it is just a piece of apparatus that you use to mount the machines, I think you can get something similar to do the same with British washing machines and dryers.