TRUaire 290 Series Fixed Bar Return Air Filter Grilles. Sizes listed below are LIST SIZES -- opening size. LIST SIZE grille frame will slide into a 12x12 drywall opening. The actual outer size of the grille frame is larger.
Table of Contents. Benign paroxysmal positional vertigo (BPPV) is a problem with the nerves and structure of the inner ear that causes you to suddenly feel dizzy. You might feel like the room is spinning around in circles or that your surroundings are moving. This feeling is called vertigo..
Benign positional vertigo. Benign positional vertigo is the most common type of vertigo. Vertigo is the feeling that you are spinning or that everything is spinning around you. It may occur when you move your head in a certain position. Benign positional vertigo is also called benign paroxysmal positional vertigo (BPPV). It is caused by a problem in the inner ear. The inner ear has fluid-filled tubes called semicircular canals. When you move, the fluid moves inside these tubes. The canals are very sensitive to any movement of the fluid.