You could use flanged cartos with it if you wanted to slide the bottom delrin piece over the whole body of the carto to the bottom each time, which would kind of be a PITA. See pbusardo's video on YouTube of the Mini Sub tank and you'll see his little experiment, it takes over 4lbs of force to get the carto to come out of this tank - ergo, you don't need a flanged carto![]()
They are not delrin end caps, they are vinyl grommets. Delrin is a hard plastic whereas the grommets on the Sub tanks are very flexible vinyl grommets. Also, they slide over the cartos very easily when the tank is not in place. Just the grommet will slide down over the carto with little to no resistance, but once you put the polycarbonate tank in place it squeezes everything together and "locks" it all in place.