Anyone use this stuff?

TAMIYA Weathering Master 6-Sets(A,B,C,D,E,F) [Japan Import] Model: https://www.amazon.com/dp/B00M66FM86?ref=cm_sw_r_mwn_dp_SH71NZTFJGX9M3D70K56&ref_=cm_sw_r_mwn_dp_SH71NZTFJGX9M3D70K56&social_share=cm_sw_r_mwn_dp_SH71NZTFJGX9M3D70K56&language=en-US

I dont think i would use alot of it, probably last me forever.  But i can see if i have a need, then the effect i want is already ready.  I wonder what the shelf life is.