Graco 206996 TSL (Throat Seal Liquid), part number 206996, supplied in a 1 gal container. TSL is the throat seal fluid that fills the wet cup above the displacement-pump packings on a piston (airless) paint sprayer; it lubricates the piston rod and keeps the upper packings from drying out, which extends packing life. Type: Throat Seal Liquid. For use with GH Big Rig Sprayers.