I spend an average of $200.00 a month buying my cartridges from this vendor, Electric Tobacconist...Each order is over $50.00. I received an order last week, only to find not one cartridge worked!!! Had to think about writing this review, all past orders were satisfactory...Will not order bulk order again...way to much to spend at a clip to find the cartridges are defective...The prices and service are good. I realize your only the vendor, not the manufacturer...but, to purchase multiple pks of 2 to find not one cartridge works might justify you looking into your vendor !!!!