The Waters ACQUITY PREMIER HSS T3 VANGUARD FIT 2.1 x 5 mm 3 pk (1.8 um) 186009473 is a medical and biological laboratory equipment attachment. It is a chromatography column used for separating and analyzing complex mixtures. The column is designed to fit the ACQUITY PREMIER HSS T3 VANGUARD FIT system and has a 2.1 x 5 mm dimension with a 1.8 um particle size. The Waters brand is known for producing high-quality laboratory equipment.