The top cap of the SVD 2.0 is tapered for a 22mm tank. I just put on a Kanger Sub Tank Mini and an Innokin Apex and they both look fine.
The Kanger has .5 and 1.2 coils available plus a RBA that you can make your own and the Apex has .5 and 2.0 but the RBA is sold separately. The Kanger is 4.5 but you can only use about 3.5 before it needs filled. Innokin now has a 5ml version of the Apex.