Not sure what make they were (it's near 20 years since I was in them). The one, an 8/16 over head, I was only night milking ever 3rd day, don't know whether that one would milk straight through, never tried. If I remember right they still had manual valves to hold the milk for recording, this was left open for normal milking. The other was a 12/12 low line. There was 2 vacuum switches on the jar, one configuration would hold the milk while milking then let it go when the cluster came off, another way would hold the milk when the cluster came off and I'm pretty sure you could milk straight through if you set the switches a 3rd way. It was something like both up, both down and one up/one down.