I purchased a clone Crown and clone rba base from FT. First try, it did not connect. Unscrewed the bottom of the rba a bit and it connects just fine. Been using it for a couple of days.
$10.57 Uwell Crown Styled Sub Ohm Tank Clearomizer - 4ml / 0.5ohm / stainless steel + glass at FastTech - Worldwide Free Shipping
$4.21 Replacement RBA Coil Head Kit for Uwell Crown Clearomizer (DIY) at FastTech - Worldwide Free Shipping
$10.57 Uwell Crown Styled Sub Ohm Tank Clearomizer - 4ml / 0.5ohm / stainless steel + glass at FastTech - Worldwide Free Shipping
$4.21 Replacement RBA Coil Head Kit for Uwell Crown Clearomizer (DIY) at FastTech - Worldwide Free Shipping