13x21_3/4x1 Exact MERV 12 Plus Carbon AC Furnace Filters 6 Pack ph-ec-tds-meters-and-solutions PhysioSpec Indoor is a full-cycle

PhysioSpec Indoor is a full-cycle spectrum optimized for rapid growth and complete plant development

Ergonomic design and comfort lock reduce stress to the hand

Hortilux's basic metal halide lamp series provide high initial and maintained lumen output

Pet & People Safe – Gentle enough to use around kids

13x21_3/4x1 Exact MERV 12 Plus Carbon AC Furnace Filters 6 Pack ph-ec-tds-meters-and-solutions PhysioSpec Indoor is a full-cycleNordic Pure Custom MERV 12 Plus Carbon air filters are made based on the actual measurements so be sure to measure your current filter to get the EXACT dimensions before ordering. As with all Nordic Pure filters, the effective life of your filter depends on the environment in which you live. We recommend changing 1 and 2 filters every 30 90 days. Our 4, 5 and 6 inch thick filters could last up to 6 months. EXACT MEASUREMENT: Furnace and air condition