3M Chromate Check Swabs are self-contained units each containing all the materials required for a rapid screening test to detect leachable Cr (VI) ions on virtually any solid surface. Inside the barrel of the swab are two glass ampoules containing a Cr (VI) reactive material and a liquid activating solution. Just crush, shake and squeeze, then RUB on most surfaces. If a pink/purple color develops on the 3M Chromate Check Swab, compare it to the Color Chart included in the instruction manual. The appearance of a pink/purple color on the swab indicates the presence of Cr (VI) at greater than 1 microgram/test area. (Look for color on the side of the tip especially if the level of Cr (Vi) is low or the reaction mix has been sucked back into the swab).2 Pack!