I have never ever seen the last one before, didn't know such a thing existed. 90% of the pumps up here have the second one and on my boat i just had to stick the nozzle in half way and it was working fine and i could feel and hear the air coming out of the vent but as soon as i stuck it in all the way the nozzle clicked like it was full after putting 5 dollars in a brand new 40 gallon tank.