The stretch top creates a vacuum seal that allows you to preserve food in the refrigerator easily and hygienically, preventing contamination and prolonging freshness. This top is especially useful in with leftovers in either metal, plastic or glass. It is even suitable for preserving fruit and vegetable halves. A vacuum seal is achieved by simply pressing down on the top. Due to the products elasticity it easily adjusts to containers of all sizes.Stretching Capacity: 5.5 - 7 inches. 10-YEAR GUARANTEE Lékué offers a 10 year warranty for manufacturer's defects. We will replace any item with the same or similar item, if the item fails during use. Warranty not effective for commercial use.