Abstract: A can sealer (for closing an opening in the top cover of a metal food or beverage can) is disclosed wherein a resilient rubber-like cup is adopted to be placed over and covering the opening, and means are provided that reach down through the opening to engage the cover so that a compressive force is exerted on the resilient cup. In the preferred embodiment, the means includes a T-shaped member the stem of which protrudes through a central aperture in the cup. A rigid backup member is placed over the resilient cup and a camming lock means is coupled to the end of the stem so that, in one position of the lock means, the end of the T-shaped member is urged toward the cup and, in the second position this urging force is removed so that the cup is free to move along the stem of the T-shaped member.