Select S&S to get extra 10% off.
Final price (before tax) for 2-pack = $39.98 * 0.9 = $35.98 (low in stock, but should allow backorders)
Final price for 4-Pack $79.98 * 0.9 = $71.98
I was in the market for 20x25x4 filters and this is by far the best price I could find for MERV-11 filters.
Product description (copied from Amazon link:
The actual filter size is 19 15/16 24 5/8 x 4 3/8 Inches
Outperforms fiberglass, washable and non-electrostatic 3-month pleated 1" home air filters for your furnace, air conditioner, or HVAC system
Exclusive Filtrete Brand 3-in-1 technology from 3M traps unwanted air particles, letting cleaner air flow through
Filtrete 1000 MPR (Microparticle Performance Rating) equates to MERV 11