standard Glare grades (Glare1 through Glare6) with typical densities ranging from , which is similar to the density of fiber. These densities are smaller than the density of 2024-T3 aluminum alloy, a common aluminum alloy in aircraft structures that is also incorporated into all but one of these Glare grades. (Glare1 uses the 7475-T761 alloy instead.) As the strength of the composite varies with fiber direction, the Glare grades differ by the number and complexity of pre-preg plies and orientations within a composite layer. Each Glare grade has A and B variants that have the same number of plies but with alternate fiber orientations. The standard Glare grades are cured in an autoclave at for 3.5 hours under , and they use the FM94 epoxy pre-preg. A single sheet of Glare may be referred to using the naming convention . The number of aluminum layers is always one more than the number of glass fiber layers, and the aluminum layer thickness is in millimeters, which can range from . (Glare1 can only consist of aluminum layers of thickness, though.) For example, Glare4B-4/3-0.4 is a Glare sheet with a Glare4 grade (using the B variant) where there are four aluminum layers and three glass fiber layers, and the thickness of each aluminum layer is . (In contrast, a typical sheet of photocopy paper is 0.097 mm (0.004 in; 4 mils) thick, while a typical business card is 0.234 mm (0.009 in; 9 mils) thick.) The thickness of a Glare grade does not need to be separately specified, because each pre-preg ply has a nominal thickness of , and the number of plies is already defined for a Glare grade number. Glare grades 1, 2, 3, and 6 have just two plies of glass fibers, so the thickness of an individual glass fiber layer is . Glare4 has three plies, so its glass fiber layers are each thick. Glare5 has four plies, with individual glass fiber layers of thickness. Glare sheets have typical overall thicknesses between . Other, less common grades and designations of aluminum/glass fiber hybrids also exist. A newer class of Glare, called High Static Strength Glare (HSS Glare), incorporates the 7475-T761 alloy and cures at using FM906 epoxy pre-preg. HSS Glare comes in three grades (HSS Glare3, HSS Glare4A, and HSS Glare4B), mirroring the plies and orientations of their corresponding standard Glare grades. Russia, which at one point was