Lennox Corporation X6667 Filter 21x26x4 MERV 10<div style="text-align: left;"><strong>[Product Information]</strong><br><ul><li>Use in Lennox PureAir PCO-20C Air Cleaner</li><li>MERV 10 Efficiency to capture particles as small as 0.3 microns</li><li>Actual Size: 20-3/4" x 25-3/4" x 3-3/4"</li><li>Replace every 6 months in normal use</li><li>Genuine Lennox OEM Filter</li></ul></div><img src="http://ecx.images-amazon.com/images/I/51Y2Yq0DsML.jpg" noproxy><img src="http://ecx.images-amazon.com/images/I/51uvgcxWQNL.jpg" noproxy>