Amazon offers the Mothers California Gold Clay Bar System, model no. 07240, for $12.93. Add it to cart via Subscribe & Save and it drops to $10.99. With free shipping, that's the lowest total price we could find by $7. It includes two clay bars, Showtime instant detailer, a microfiber towel, and purports to remove embedded grains of metal, tree sap, airborne environmental deposits, and paint overspray.

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