Can I Use a 1-Inch Furnace Filter Instead of 4-Inch?

I have a house where the furnace has a 25 x 1 wide slot in the air intake where I slide the 16x25x1 filter in from the top

First, locate the filter slot in your furnaceair handler Some homes have filters behind their return vents as well Furnace filter size is measured using

furnace filter slot FilterLock can be used with any 1 in air filter to improve indoor air quality and reduce energy consumption The patented, 1-size-fits-all product

witch doctor wild slot furnace filter The problem is you might think you are doing everything correctly but if you have