I use a " fifty-one trio redline " and am wondering if anybody knows of a chart or something that shows what parts will interchange between different brands? I bought a 6 pack of "21st Century" brand of cartridges from a local smokeshop. They worked ok but left a slight space between the cartridge and battery. Would have either been due to a shorter cartridge or that my atomizer is longer than what the "21st Century" brand has. Mine is the regular cigarette look alike type of electronic cigarette.