BDC COILS
These BDC (Bottom Dual Coil) coils are suitable for many of Aspire's tanks, including the following:

K1
ET
ET-S
CE5 (Available Here)
CE5-S
Viva Nova
Mini Viva Nova
Viva Nova - S

Examples are shown below.

If you require BVC (Bottom Vertical Coil) heads, they can be found here. BDC & BVC coils can be used Interchangeably.