Product review (1 stars): I recommend you do not buy
I recommend you do not buy.  The price for this single filter was only one dollar less than several other options for  Aprilaire #35 filters that contain two filters in the order.  Because this was pictured the same and along side  two-filter options I was fooled into assuming this was also two filters,
So naturally I picked the order that was slightly less expensive.  Hopefully you will read this and not make my mistake.