B12 vs. W18? We source our lashes from two different manufacturers to obtain a range of adhesive qualities in our lash strips. Our black trays (marked “B”) have a tackier quality, while our white trays (“W”) have a milder adhesive strip. The number after the letter (e.g. W18) refers to the number of rows of lashes you get in the tray. Prices vary by manufacturer, accounting for the difference in number.