Abstract: The present invention is directed to a filter cartridge that provides for a secure dust tight seal and is easily inserted and removed from a filtration unit. The filter cartridge includes a cartridge unit having a filter element, a bottom cap and a top boot and a sealing sleeve for insertion into the interior of the top boot. The top boot has an outside diameter which is slightly smaller than the inside diameter of the opening in a tube sheet into which the filter cartridge is to be inserted so that the cartridge may be easily inserted into and removed from the opening in a tube sheet. The top boot is also provided with a sealing ridge, which is located in the inside of the boot at the sealing point. The inside diameter of the sealing ridge is smaller than the cartridge boot and the sealing sleeve. When the sealing sleeve is inserted into the cartridge boot, the sealing sleeve contacts the sealing ridge and causes an increase in diameter of the sealing ridge.