12 pack furnace filters on sale

[OWC Jamie]

Ammo wrote:
Does anyone know if you can stack multiple 1" filters to make one 4" filter?

It will always be 4 one inch filters
and likely one hell of a restriction

you can use a more restrictive filter media by increasing the square feet of surface area exposed ( large pleats accomplish this in a thicker filter )

In (simple non-exponential ) theory you could stack those 4 filters but you would have to make them 4 times the size.