Poolmaster 12408 Replacement Filter Cartridge for Watkins 31489 Filter<div style="text-align: left;"><strong>[Product Information]</strong><br><ul><li>Equivalent to the following replacement filter cartridges; Pleatco PWK30 and Unicel C-6430</li><li>The top of the replacement filter cartridge is open 1-15/16 and the bottom is open 1-15/16</li><li>High quality spun bonded polyester material for exceptional water filtration</li><li>Premium grade polyurethane and plastisol end caps</li></ul></div><img src="http://ecx.images-amazon.com/images/I/31zSK8wT%2BzL.jpg" noproxy>