I bought this directly from Coil Master to replace my standard 521 TAB. Turns out my original 521 Tab just had a bad connection that I re-soldered. This new design is larger and holds 2 18650 batteries. I've only tested this to make sure it works but never "built on it". I'm sending it in the original box with everything included as new. Asking $60 shipped USPS priority flat rate. PP F&F or fees on you I will also consider trades/partial trades for mid to high end single coil RTA,RDA or older DNA60, DNA40, DNA30 boxes working or not.