This product consists of a solution of Evans Blue dye in PBS with 0.04% sodium azide as preservative. The volume is 3.5 mL. It is conveniently packaged in a plastic dropper vial. This product can be used in up to 75 tests, using one drop per test (at approximately 45 uL per drop).

BlockOut Counterstain binds nonspecifically, fluorescing red using a fluorescein filter setting, thereby providing and enhancing contrast with cells that are fluorescing green due to binding of fluorescein. Generally, an incubation period of 1 minute with counterstain, after the antibody step, gives good results.