While you've requested a product description for a 'Men's light blue tank top size L,' the image provided features a different garment. The shirt depicted is a men's long-sleeved dress shirt with a vertical striped pattern in shades of blue, white, and possibly subtle hints of other colors. The fabric appears to be a lightweight, possibly cotton blend suitable for business casual or semi-formal occasions. Details include a pointed collar, a front chest pocket, and button cuffs. This shirt's classic design and muted color palette would make it a versatile addition to a man's wardrobe. Since this description does not match the tank top you've asked about, please provide the appropriate image or details for the intended product.