The 1660005 is a clone clearomizer. Lot of them are made badly, not sealing or coil head doesn't fit properly.
I've been using the 1425902 for a long time now and I've had a problem. I use them in genuine Kanger clearomizers and these cheap Evods. This Evod (
SKU 1363501) is a clone but is cheap and works well with the 1425902 heads. Try that.
Edited on 8/29/2014 at 1:56 AM. Reason: