Graco 206994 TSL (Throat Seal Liquid), part number 206994, supplied in a 8 oz 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 Oil. For use with Airless Paint Sprayer.