Sorry guys I read the email notification they sent me wrong. Here is what it said:
SDMKII 901-510 Atomizer Conversion kits, LR and Regular
We will be receiving in the next few days the SDMKII 901-510 conversion kit.
The Screwdriver is a fantastic
device but some users requested we should have a flexible atomizer choice for it. We now will have, all SD full kits will have 4 atomizers as standard 2 x 901 and 2 x 510.