Different builds, or on different mods, even different flavor being used in each lol. Significant other always asks me why I got so many toppers on my comp desk/vape stand/vape workstation, compared to mods and such to match them up with. Got my favorite mods, and mods cost more than a new topper, presently at a 3 toppers to 1 mod ratio, and 2/3s of those are drippers, though my RTA collection is growing by the week as I've backed down from clouding to all flavor and tootle puffing anymore.