16 oz Invertatop, Standard Valvetop 6/pack 53mm opening. Dispensing made easy. Unique design. Sanitation guaranteed. Fill and store "inverted" for quick and easy use. Dual openings - easy to clean and fill. FDA approved fodd grade polyethylene material. Leakproof "soft" polyethylene PefectFlex for fast prep. InvertaTopstandard valve design works well with olive oil & vinegar and high viscocity, slow-flowing condiments such as bar-b-que and mayonnaise.