Graco 334128A is a repair kit for replacing throat seal kits in professional settings. It comes with a preassembled throat repair kit that includes a backup washer, seal, and washer, all of which are properly positioned on top of the packing housing. The kit also includes an o-ring, packing nut, and washer. To use the kit, you will need to relieve pressure, unscrew the packing nut, and remove the old o-ring and washer.