Doubled my order and Groupon couldn't fulfill the order. Didn't get notified. Only got half of my order and had to start making phone calls. Had to be reimbursed for the missing half. Groupon was timely in returning my money, but why offer being able to purchase more than one at a time when you don't deliver.
I am writing the review primarily to contradict a November 2015 rating. The filters I received were 4 in a box wrapped in cellophane with a flyer inside giving a full description. The first bullet point description is: Efficiency up to MERV 13.