A latch unit for releasably securing a plastic lid 15 to a tank-like container 11 or for releasably securing another covering over the container. The container may be the tank of an electric vacuum cleaner. There are a plurality of the latch units spaced along the edge of the lid or covering and engageable with a bead around the open end of the tank. Each latch unit includes a cage 19 at the edge of the lid or of the covering and includes a latch element 20 molded of resilient plastic material. One end 30 of the latch element protrudes from the cage and is hand engageable for moving the element between releasing and holding positions. The other end of the element is provided with a hook 26 that engages a cage formation to form a pivot for the element. A normally bowed intermediate section 31 of the element connects opposite ends of the element, and is stressed to provide a biasing force that holds the element mounted to the cage. This biasing force also provides detent forces required to maintain the latch element 20 in the holding or releasing position to which it is operated. A detent 34 at the intermediate section of the element engages an upstanding wall of the cage to hold the element in the releasing position.