Filterbuy Optimal Smoke & Allergy Defense in the 16x25x1 size is rated MERV 13. The actual filter measures 15.50 x 24.50 x 0.75″ — same rule as any other 1″ filter: the printed nominal size is rounded up, the real filter is slightly smaller so it fits the frame.

Buying more than once a year? Amazon's Subscribe & Save typically knocks a few percent off recurring filter orders — worth toggling on at checkout if you're going to reorder this size anyway.