Lucky that Costco Ringwood is within 5km from my home. They had more than 10 in stock and they mentioned they have changed the model number of the 4 Packs to 115316.
If you guys go to other stores might able to ask them if they have the 4 packs in new model number in stock.
I've got some from Hn deal. Love to know peoples experience with them. Has anyone performed any tests?