Actual size is 20.75 x 20.63 x 5. Accumulair brand 20x21x5 Electro-Air SST 16C28S-010 compatible whole house filters, specifically designed to substitute for the name brand Electro-Air SST 16C28S-010 air filters. Completely constructed so no forming or combs needed. MERV rated to ASHRAE 52.2 test specs assuring filtration equal to the original brand Electro-Air SST 16C28S-010 filters. Notice: The sample air filter pic as shown is not true to size and is included to show style purposes only. Company names and Electro-Air SST 16C28S-010 P/N used for air filter substitution identification purposes.