Bauway Jay tank/MT3. It is a Metal Tube, Replaceable Bottom Coil cartomizer with a non-removable mouthpiece. It is filled from the bottom This design is similar to a MTBCC, MT3 and a Jag Tank with it's replaceable bottom coil unit. This tank will fit most eGo style batteries that have the outer threads. It will not fit in a standard 510 thread battery as it uses the outer threads that are most commonly used by "cones" or "gap fillers".