These are countertop rinser sinks that are meant to rinse out your frothing pitchers between frothing operations. They connect to COLD water only. They do not sterilize the pitchers, but they do clean them out and cool them down. Cooling them down will give you a better froth.
One sink is a standalone unit in its own cabinet that can be placed wherever itís convenient. One is meant to be mounted into the counter (meaning that you will cut the counter out to hold it. And one is an on-counter longer unit that only stands an inch high, but itís water connections go through the counter.