Koch Multi-Sak MERV 13 Extended Surface Air Filter – 20x24x18 in, 6-Pack (Model 208-105-318)

Description

This 20″ × 24″ × 18″ Koch Multi-Sak Extended Surface Bag filter (part number 208-105-318) is a commercial extended-surface bag filter rated MERV 13, designed for commercial and industrial air handlers operating at face velocities from 500 to 3000 CFM.

What makes a bag filter different

Extended-surface bag (or pocket) filters use multiple deep media pockets instead of a flat pleated pack. The result is dramatically more filter surface area in the same footprint — typically 10–20× what a panel filter provides — which means higher dust-holding capacity, longer service life, and lower average pressure drop. They’re the workhorse filter in most large commercial air handlers.

Media and construction

• Media: 100% synthetic bag media with progressively loaded pleats. Progressively loaded from upstream to downstream for balanced dust capture.
• Pocket construction: Rigid support members maintain pocket shape through the filter’s service life, preventing collapse under loading.
• Frame: Galvanized steel header (single or double) for standard side-access housings.
• Rating: MERV 13 per ASHRAE 52.2.

What MERV 13 captures

Very fine particles including smoke, bacteria-sized particles, and virus carriers attached to larger droplets, on top of everything MERV 11 captures. Commonly specified for commercial spaces with higher indoor-air-quality requirements and for homes with wildfire smoke or air-quality concerns. Ensure your HVAC system is rated for the increased static pressure.

Typical applications

Commercial office-building air handlers, school HVAC, retail, hospitality, light industrial ventilation, and as high-efficiency final filters in multi-stage systems.

Also worth considering

Shopping on price? Our house brand PrimeShield Elite (MERV 13) covers the same efficiency tier across common residential and commercial sizes and is usually the better value. Choose this branded option when your equipment spec sheet or facilities team calls for it specifically.

Questions on fit, quantity, or a commercial quote?

Need a size that isn’t listed, a different pack count, or a quote for a commercial order? Get in touch — we handle facilities and commercial orders daily and can usually match or beat distributor pricing.

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