If you ever want to order a back up and are willing to wait 2 to 7 weeks for delivery you can save a lot. you can get the exact same rba that you just bought for $2.38 and free shipping. Link below
$2.38 Replacement Rebuildable RBA Plus Coil Head for SUBTANK Mini Clearomizer (SS, 0.5ohm) at m.FastTech.com
$2.38 Replacement Rebuildable RBA Plus Coil Head for SUBTANK Mini Clearomizer (SS, 0.5ohm) at m.FastTech.com