The Merlin RDTA is a 24mm genesis-style atomizer with a 3.5ml capacity. It was clearly designed with builders in mind, because the post holes are absolutely gigantic and it also has huge under-coil airflow slots. It uses a unique top filling system that uses a port directly in the center of the build deck, which is plugged while the topcap is on. Once you get past the headache of building, wicking is a breeze and so is top-filling method. This RDTA vapes amazingly at high wattages, keeps up with wicking, and gives great flavor compared to other 24mm RDTAs that ever made.